WorldWideScience

Sample records for vibrationally mediated photodetachment

  1. Vibrational Fano resonances in the photodetachment of dipole-bound anions

    International Nuclear Information System (INIS)

    Edwards, Stephen T; Tully, John C; Johnson, Mark A

    2012-01-01

    A simple model for the photodetachment of dipole-bound anions is proposed where non-adiabatic coupling of vibrational states leads to a Fano resonance in the spectrum. It is found that the shape of the photodetachment spectrum depends significantly on the parameter representing molecular polarizability. The model is also applied to a Fano profile observed in the photodetachment of small water cluster anions.

  2. Vibration-dependent angular anisotropy in the photodetachment of O{sub 2}{sup -}, viewed with velocity-map imaging

    Energy Technology Data Exchange (ETDEWEB)

    Gibson, S T; Cavanagh, S J; Lewis, B R [Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia); Gascooke, J R [School of Chemistry, Physics and Earth Sciences, Flinders University, SA 5001 (Australia); Mabbs, R [Department of Chemistry, Washington University, St Louis MO 63930-4899 (United States); Sanov, A, E-mail: Stephen.Gibson@anu.edu.a, E-mail: Steven.Cavanagh@anu.edu.a [Department of Chemistry, University of Arizona, Tucson AZ 85721-0041 (United States)

    2009-11-01

    The photodetachment spectrum of O{sub 2}{sup -} has been measured at a number of wavelengths using velocity-map imaging. The electron kinetic-energy resolution (< 5 meV) is sufficient to resolve the anion fine-structure splitting, vibrational and electronic structure. The electron angular distribution varies with the electron kinetic-energy, with a different behaviour for each vibronic band.

  3. Probing the Vibrational Spectroscopy of the Deprotonated Thymine Radical by Photodetachment and State-Selective Autodetachment Photoelectron Spectroscopy via Dipole-Bound States

    Science.gov (United States)

    Huang, Dao-Ling; Zhu, Guo-Zhu; Wang, Lai-Sheng

    2016-06-01

    Deprotonated thymine can exist in two different forms, depending on which of its two N sites is deprotonated: N1[T-H]^- or N3[T-H]^-. Here we report a photodetachment study of the N1[T-H]^- isomer cooled in a cryogenic ion trap and the observation of an excited dipole-bound state. Eighteen vibrational levels of the dipole-bound state are observed, and its vibrational ground state is found to be 238 ± 5 wn below the detachment threshold of N1[T-H]^-. The electron affinity of the deprotonated thymine radical (N1[T-H]^.) is measured accruately to be 26 322 ± 5 wn (3.2635 ± 0.0006 eV). By tuning the detachment laser to the sixteen vibrational levels of the dipole-bound state that are above the detachment threshold, highly non-Franck-Condon resonant-enhanced photoelectron spectra are obtained due to state- and mode-selective vibrational autodetachment. Much richer vibrational information is obtained for the deprotonated thymine radical from the photodetachment and resonant-enhanced photoelectron spectroscopy. Eleven fundamental vibrational frequencies in the low-frequency regime are obtained for the N1[T-H]^. radical, including the two lowest-frequency internal rotational modes of the methyl group at 70 ± 8 wn and 92 ± 5 wn. D. L. Huang, H. T. Liu, C. G. Ning, G. Z. Zhu and L. S. Wang, Chem. Sci., 6, 3129-3138 (2015)

  4. Photodetachment now

    International Nuclear Information System (INIS)

    Fink, J.H.

    1987-10-01

    To illustrate the feasibility of photodetachment, the author describes a conceptual design of photo-neutralizers for 0.5 and 3.0 MeV deuterium beams. The negative ions are stripped in optical cavities using large mirrors with higher than 99.99% reflectivity. The neutralizers are illuminated by an array of Nd:YAG slab-lasers emitting about 30 kW/m of light per unit length, while the mirrors are exposed to an irradiance of the order of 100 MW/m 2 . Details of the photodetachment cells and the laser configurations have not been resolved. 9 refs., 6 figs

  5. Correlation in photodetachment

    International Nuclear Information System (INIS)

    Pegg, D.J.

    1992-01-01

    Electron correlation plays a major role in all aspects of the photodetachment of an electron from a negative ion. Photodetachment measurements are well suited to investigate the relatively short range forces associated with correlation due to the absence of the long range Coulomb interaction. Measurements of electron affinities, asymmetry parameters and cross sections are described to illustrate the influence of correlation on photodetachment

  6. Correlation in photodetachment

    International Nuclear Information System (INIS)

    Pegg, D.J.; Tennessee Univ., Knoxville, TN

    1991-01-01

    Electron correlation plays a major role in all aspects of the photodetachment of an electron from a negative ion. Photodetachment measurements are well suited to investigate the relatively short range forces associated with correlation due to the absence of the long range Coulomb interaction. Measurements of electron affinities, asymmetry parameters and cross sections are described to illustrate the influence of correlation on photodetachment. 25 refs., 4 figs

  7. Photodetachment of metastable He-

    International Nuclear Information System (INIS)

    Thompson, J.S.; Dellwo, J.; Compton, R.N.

    1990-01-01

    A crossed-beams apparatus has been used to measure angular distributions and cross sections for photoelectron detachment from metastable He - . Energy- and angle-resolved electron spectroscopy was used to investigate the spectral dependences of the angular distribution of the photoelectrons. The angular distributions along with photoelectron yield measurements were used to determine the cross sections for photodetachment of He - (2 4 P) via the energy resolved He(2 3 P) and He(2 3 S) exit channels. The precision of the cross section measurements was enhanced by exploiting the kinematic effects associated with detachment from a fast beam source. Calculated cross sections for the photodetachment of H - were used to establish an absolute scale for the He - cross section measurements

  8. The Photodetachment Microscope

    Energy Technology Data Exchange (ETDEWEB)

    Blondel, C.; Delsart, C.; Dulieu, F. [Laboratoire Aime-Cotton, Centre National de la Recherche Scientifique II, Batiment 505, F-91405 Orsay cedex (France)

    1996-10-01

    Br{sup {minus}} ions undergo photodetachment in the presence of an electric field. As a result of the photoexcitation process, the emitted electron{close_quote}s wave function extends to infinity, but inside a paraboloid elongated in the direction of the field. A position-sensitive detector set across the electron emission axis makes it possible to image the transverse factor of the atomic wave function. A ring pattern is observed, with a number of dark rings which is analogous to the first parabolic quantum number of the LoSurdo-Stark problem. {copyright} {ital 1996 The American Physical Society.}

  9. Collective phenomena in negative ion photodetachment

    International Nuclear Information System (INIS)

    Ivanov, V.K.

    1996-01-01

    The many-electron collective effects in negative ion photodetachment are discussed. The calculations of photodetachment cross sections and photoelectron angular distributions have been performed within the Many-Body Theory Methods. It is shown that the role of many-electron interactions leading to the collective effects like dynamical polarizability, interchannel interaction, core polarization, core relaxation, is very important to describe the photodetachment processes. (author)

  10. Nuclear catalysis mediated by localized anharmonic vibrations

    OpenAIRE

    Dubinko, Vladimir

    2015-01-01

    In many-body nonlinear systems with sufficient anharmonicity, a special kind of lattice vibrations, namely, Localized Anharmonic Vibrations (LAVs) can be excited either thermally or by external triggering, in which the amplitude of atomic oscillations greatly exceeds that of harmonic oscillations (phonons) that determine the system temperature. Coherency and persistence of LAVs may have drastic effect on quantum tunneling due to correlation effects discovered by Schrodinger and Robertson in 1...

  11. Electronic and vibrational spectroscopy and vibrationally mediated photodissociation of V+(OCO).

    Science.gov (United States)

    Citir, Murat; Altinay, Gokhan; Metz, Ricardo B

    2006-04-20

    Electronic spectra of gas-phase V+(OCO) are measured in the near-infrared from 6050 to 7420 cm(-1) and in the visible from 15,500 to 16,560 cm(-1), using photofragment spectroscopy. The near-IR band is complex, with a 107 cm(-1) progression in the metal-ligand stretch. The visible band shows clearly resolved vibrational progressions in the metal-ligand stretch and rock, and in the OCO bend, as observed by Brucat and co-workers. A vibrational hot band gives the metal-ligand stretch frequency in the ground electronic state nu3'' = 210 cm(-1). The OCO antisymmetric stretch frequency in the ground electronic state (nu1'') is measured by using vibrationally mediated photodissociation. An IR laser vibrationally excites ions to nu1'' = 1. Vibrationally excited ions selectively dissociate following absorption of a second, visible photon at the nu1' = 1 CO2, due to interaction with the metal. Larger blue shifts observed for complexes with fewer ligands agree with trends seen for larger V+(OCO)n clusters.

  12. Atomic polarizability in negative-ion photodetachment

    International Nuclear Information System (INIS)

    Watanabe, S.; Greene, C.H.

    1980-01-01

    The influence of a strong atomic polarizability on photodetachment processes is isolated. In a model study of K - photodetachment near the 4p/sub 1/2/, 4p/sub 3/2/ levels of K, the polarizability (α/sub 4p/ approx. = 600a 3 0 ) is shown to cause a striking energy dependence of the parameters which determine the cross section. This study extends the effective range theory of O'Malley, Spruch, and Rosenberg to a broader energy range and to multichannel systems. An appendix provides a derivation of the polarization potential (and correction terms) starting from the electron-atom close-coupling equations, showing some new features

  13. Photodetachment of negative C60- ions

    International Nuclear Information System (INIS)

    Amusia, M.Ya.; Baltenkov, A.S.; Krakov, B.G.

    1998-01-01

    A model that describes the electron structure of negative fullerene C 60 - ions is proposed. The model contains only two experimentally observed parameters, namely the fullerene radius and the affinity energy of the electron to neutral C 60 . In the frame of this model, cross sections are calculated of elastic scattering of slow electrons on neutral fullerene, of C 60 - photodetachment near the threshold of this process and of radiative recombination of slow electrons with neutral fullerenes. (orig.)

  14. Inner-shell photodetachment from Ru-

    International Nuclear Information System (INIS)

    Dumitriu, I.; Gorczyca, T. W.; Berrah, N.; Bilodeau, R. C.; Pesic, Z. D.; Rolles, D.; Walter, C. W.; Gibson, N. D.

    2010-01-01

    Inner-shell photodetachment from Ru - was studied near and above the 4p excitation region, 29-to-91-eV photon energy range, using a merged ion-photon-beam technique. The absolute photodetachment cross sections of Ru - ([Kr]4d 7 5s 2 ) leading to Ru + , Ru 2+ , and Ru 3+ ion production were measured. In the near-threshold region, a Wigner s-wave law, including estimated postcollision interaction effects, locates the 4p 3/2 detachment threshold between 40.10 and 40.27 eV. Additionally, the Ru 2+ product spectrum provides evidence for simultaneous two-electron photodetachment (likely to the Ru + 4p 5 4d 6 5s 2 state) located near 49 eV. Resonance effects are observed due to interference between transitions of the 4p electrons to the quasibound 4p 5 4d 8 5s 2 states and the 4d→εf continuum. Despite the large number of possible terms resulting from the Ru - 4d open shell, the cross section obtained from a 51-state LS-coupled R-matrix calculation agrees qualitatively well with the experimental data.

  15. Pacinian channel mediated vasoconstriction in the fingers during vibration exposure

    OpenAIRE

    Ye, Ying

    2013-01-01

    A review of the literature showed that acute vascular responses to hand-transmitted vibration depend on the magnitude, the frequency, and the duration of the vibration but the mechanisms involved in the immediate vasoconstriction on exposure to vibration are not clear. This research was designed to advance understanding of the relation between the characteristics of vibration and changes in vascular circulation on exposed hands, and to develop a model of the mechanoreceptor channel involved i...

  16. Photodetachment of H− near a Hard Spherical Surface

    International Nuclear Information System (INIS)

    Haneef, M.; Rahman, A.; Ahmad, Iftikhar; Afaq, A.

    2012-01-01

    The photodetachment of a hydrogen negative ion (H − ) near a hard spherical surface is investigated by using the theoretical imaging method. The surface is oriented in such a fashion that the laser polarization direction is perpendicular to the principal axis of the spherical surface. Analytical expressions are derived for the detached-electron flux and photodetachment cross section. Strong interference patterns are observed in the detached-electron flux, while no visible oscillations are found in the photodetachment cross section. (atomic and molecular physics)

  17. Chemical Reactions Triggered Using Electrons Photodetached from "Clean" Distributions of Anions Deposited in Cryogenic Matrices via Counterion Codeposition.

    Science.gov (United States)

    Ludwig, Ryan M; Moore, David T

    2014-09-04

    Application of matrix isolation spectroscopy to ionic species is typically complicated by the presence of neutral contaminants during matrix deposition. Herein we demonstrate that simultaneous deposition of balanced currents of counterions with mass-selected ions of interest generates "clean" distributions of matrix-isolated metal carbonyl anions, where the only bands appearing in the CO-stretching region of the vibrational spectrum arise from ions. (Neutrals are initially absent.) Photodetachment by mild irradiation with visible light leads to complete conversion of the anions into their corresponding neutral species. The photodetached electrons, in turn, initiate covalent chemistry, inducing C-C bond formation following electron-capture by CO van der Waals dimers to produce trans-OCCO(-). The initial clean distribution of ions enables clear connections to be drawn between the spectral changes occurring at each experimental step, thus demonstrating the potential of the counterion codeposition technique to facilitate detailed studies of chemistry involving ions and electron transfer in cryogenic matrices.

  18. Simulation of the photodetachment spectrum of HHfO- using coupled-cluster calculations

    Science.gov (United States)

    Mok, Daniel K. W.; Dyke, John M.; Lee, Edmond P. F.

    2016-12-01

    The photodetachment spectrum of HHfO- was simulated using restricted-spin coupled-cluster single-double plus perturbative triple {RCCSD(T)} calculations performed on the ground electronic states of HHfO and HHfO-, employing basis sets of up to quintuple-zeta quality. The computed RCCSD(T) electron affinity of 1.67 ± 0.02 eV at the complete basis set limit, including Hf 5s25p6 core correlation and zero-point energy corrections, agrees well with the experimental value of 1.70 ± 0.05 eV from a recent photodetachment study [X. Li et al., J. Chem. Phys. 136, 154306 (2012)]. For the simulation, Franck-Condon factors were computed which included allowances for anharmonicity and Duschinsky rotation. Comparisons between simulated and experimental spectra confirm the assignments of the molecular carrier and electronic states involved but suggest that the experimental vibrational structure has suffered from poor signal-to-noise ratio. An alternative assignment of the vibrational structure to that suggested in the experimental work is presented.

  19. Photodetachment in the gaseous, liquid, and solid states of matter

    International Nuclear Information System (INIS)

    Christophorou, L.G.; Datskos, P.G.; Faidas, H.

    1994-01-01

    We have made absolute cross section measurements of laser photodetachment of C 6 F - 6 ions embedded in gaseous tetramethylsilane (TMS) and compared the results at low gas densities with measurements in nonpolar liquids and solids. The measurements indicate that the photodetachment cross section of C 6 F - 6 in gaseous TMS is about three times larger than in liquid TMS. This is rationalized by considering the effect of the medium on both the photoabsorption and the autodetachment processes. The photodetachment cross section in both the gas and the liquid exhibits (at least) two maxima due to autodetaching negative ion states. It is argued that these are due to σ*→σ* transitions in C 6 F - 6 . The relative positions of these ''superexcited'' anionic states did not change appreciably in going from the gas to the liquid and the solid, indicating similar influences of the medium on them. As expected, the photodetachment threshold in the condensed phase is shifted to higher energies compared to the gaseous phase. This shift is consistent with recent photoelectron studies of photodetachment of C 6 F - 6 clusters. The present study clearly shows that the photodetachment from negative ions embedded in all states of matter proceeds directly or indirectly via negative ion autodetaching states, and that for nonpolar media, the effect of the medium can be accounted for by considering the macroscopic properties of the medium described by its dielectric constant ε and refractive index n

  20. Partial cross sections in H- photodetachment

    International Nuclear Information System (INIS)

    Halka, M.

    1993-04-01

    This dissertation reports experimental measurements of partial decay cross sections in the H - photodetachment spectrum. Observed decays of the 1 P 0 H -** (n) doubly-excitedresonances to the H(N=2) continuum are reported for n=2,3, and 4 from 1990 runs in which the author participated. A recent analysis of 1989 data revealing effects of static electric fields on the partial decay spectrum above 13.5 eV is also presented. The experiments were performed at the High Resolution Atomic Beam Facility. the Los Alamos Meson Physics Facility, with a relativistic H - beam (β=0.842)intersecting a ND:YAG laser. Variation of the intersection angle amounts to Doppler-shifting the photon energy, allowing continuous tuning of the laser energy as viewed from the moving ions' frame

  1. Photodetachment of Isolated Bicarbonate Anion: Electron Binding Energy of HCO3-

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xue B.; Xantheas, Sotiris S.

    2011-04-29

    We report the first direct photodetachment photoelectron spectroscopy of HCO3 in the gas phase under low temperature conditions. The observed photoelectron spectra are complicated due to excitations of manifolds in both vibrational and electronic states. A long and single vibrational progression with a frequency of 530 ± 20 cm-1 is partially resolved in the threshold of the T=20 K, 266 nm spectrum. The adiabatic electron detachment energy (ADE) of HCO3, or in other words the electron affinity (EA) of neutral HCO3, is experimentally determined from the (0-0) transition to be 3.680 ± 0.015 eV. High-level ab initio calculations at the CCSD(T) level of theory produce an anharmonic frequency of 546 cm-1 for HCO3 and a value of 3.62 eV for the (0,0) transition, both in excellent agreement with the experimentally determined values.

  2. H- photodetachment and radiative attachment for astrophysical applications

    Science.gov (United States)

    McLaughlin, B. M.; Stancil, P. C.; Sadeghpour, H. R.; Forrey, R. C.

    2017-06-01

    We combine R-matrix calculations, asymptotic relations, and comparison to available experimental data to construct an H- photodetachment cross section reliable over a large range of photon energies and take into account the series of auto-detaching shape and Feshbach resonances between 10.92 and 14.35 eV. The accuracy of the cross section is controlled by ensuring that it satisfies all known oscillator strength sum rules, including contributions from the resonances and single-photon double-electron photodetachment. From the resulting recommended cross section, spontaneous and stimulated radiative attachment rate coefficients are obtained. Photodetachment rates are also computed for the standard interstellar radiation field, in diffuse and dense interstellar clouds, for blackbody radiation, and for high redshift distortion photons in the recombination epoch. Implications are investigated for these astrophysical radiation fields and epochs.

  3. Photodetachment from negative ions with ns2 subshells

    International Nuclear Information System (INIS)

    Ivanov, V.K.; Ipatov, A.N.; Krukovskaya, L.P.

    1997-01-01

    The theoretical study on multielectron effects in processes of electrons photodetachment from the Cu - and Cr - negative ions is carried out. The calculations were accomplished within the frames of the model, based on the approximation of random phases with exchange with simultaneous account for impact of the static polarization potential and the shell static rearrangement. The calculational results of photodetachment cross sections of the external 4s-electrons from Cu - and Cr - are presented and comparison with the available experimental data and the results of other calculations is carried out

  4. 2001 Gordon Research Conference on Photoions, Photoionization and Photodetachment. Final progress report [agenda and attendees list

    International Nuclear Information System (INIS)

    Johnson, Mark

    2001-01-01

    The Gordon Research Conference on Photoions, Photoionization and Photodetachment was held at Williams College, Williamstown, Massachusetts, July 8-13, 2001. The 72 conference attendees represented the spectrum of endeavor in this field, coming from academia, industry, and government laboratories, and including US and foreign scientists, senior researchers, young investigators, and students. Emphasis was placed on current unpublished research and discussion of the future target areas in this field. There was a conscious effort to stimulate discussion about the key issues in the field today. Time for formal presentations was limited. Sessions included the following topics: Vibrational structure, Time resolved studies: nuclear wavepackets, Valence photoionization, Clusters and networks, Resonance structures and decay mechanisms, Ultrafast photoionization, Threshold photoionization, Molecule fixed properties, and Collisional phenomena

  5. Electron-Mediated Phonon-Phonon Coupling Drives the Vibrational Relaxation of CO on Cu(100)

    Science.gov (United States)

    Novko, D.; Alducin, M.; Juaristi, J. I.

    2018-04-01

    We bring forth a consistent theory for the electron-mediated vibrational intermode coupling that clarifies the microscopic mechanism behind the vibrational relaxation of adsorbates on metal surfaces. Our analysis points out the inability of state-of-the-art nonadiabatic theories to quantitatively reproduce the experimental linewidth of the CO internal stretch mode on Cu(100) and it emphasizes the crucial role of the electron-mediated phonon-phonon coupling in this regard. The results demonstrate a strong electron-mediated coupling between the internal stretch and low-energy CO modes, but also a significant role of surface motion. Our nonadiabatic theory is also able to explain the temperature dependence of the internal stretch phonon linewidth, thus far considered a sign of the direct anharmonic coupling.

  6. Studies on the substrate mediated vibrational excitation of CO/Si(100) by means of SFG spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Han, Xu; Lass, Kristian; Balgar, Thorsten; Hasselbrink, Eckart [Universitaet Duisburg-Essen, Fachbereich Chemie, 45117 Essen (Germany)

    2009-07-01

    Vibrational excitations of adsorbates play an important role in chemical reaction dynamics. In the past decade CO on solid surfaces was chosen as adequate model system for studying vibrational relaxation dynamics. Our work is focused on the energy dissipation of vibrationally excited CO adsorbed on a silicon surface by means of IR/Vis sum frequency generation (SFG) spectroscopy. Here we present studies on substrate mediated excitation of vibrational modes of CO on Si(100) induced by UV radiation. We suppose the observation of highly excited internal stretch vibrations of CO caused by hot electrons generated within the silicon substrate.

  7. Photodetachment of H ion in crossed gradient electric and magnetic ...

    Indian Academy of Sciences (India)

    2016-10-13

    Oct 13, 2016 ... ion in a gradient electric field, the Hamiltonian of the detached electron has three degrees of freedom, which makes the dynamical behaviour of the detached electron complex. Photodetachment cross-section for vari- ous external fields and the laser polarization are calculated and displayed. A comparison ...

  8. Full-dimensional characterization of photoelectron spectra of HOCO− and DOCO− and tunneling facilitated decay of HOCO prepared by anion photodetachment

    International Nuclear Information System (INIS)

    Wang, Jun; Li, Jun; Guo, Hua; Ma, Jianyi

    2014-01-01

    The photodetachment of both the HOCO − and DOCO − anions is investigated using full-dimensional quantum wave packets on new ab initio based global potential energy surfaces for both the neutral and anionic species. The calculated electron affinities and neutral fundamental vibrational frequencies of both isotopomers are in good agreement with available experimental data. The measured photoelectron spectra are also accurately reproduced, further validating the accuracy of the potential energy surfaces. In addition, strong mode specificity is found in the lifetimes of the HOCO vibrational features and the tunneling facilitated predissociation rates to H + CO 2 are rationalized using the recently proposed sudden vector projection model

  9. Photodetachment of negative ion in a gradient electric field near a metal surface

    International Nuclear Information System (INIS)

    Liu Tian-Qi; Wang De-Hua; Han Cai; Liu Jiang; Liang Dong-Qi; Xie Si-Cheng

    2012-01-01

    Based on closed-orbit theory, the photodetachment of H − in a gradient electric field near a metal surface is studied. It is demonstrated that the gradient electric field has a significant influence on the photodetachment of negative ions near a metal surface. With the increase of the gradient of the electric field, the oscillation in the photodetachment cross section becomes strengthened. Besides, in contrast to the photodetachment of H − near a metal surface in a uniform electric field, the oscillating amplitude and the oscillating region in the cross section of a gradient electric field also become enlarged. Therefore, we can use the gradient electric field to control the photodetachment of negative ions near a metal surface. We hope that our results will be useful for understanding the photodetachment of negative ions in the vicinity of surfaces, cavities, and ion traps. (atomic and molecular physics)

  10. Photodetachment of the H− ion in a linear time-dependent electric field

    International Nuclear Information System (INIS)

    Wang, De-Hua; Chen, Zhaohang; Cheng, Shaohao

    2016-01-01

    Using the time-dependent closed orbit theory, we study the photodetachment of the H − ion in a linear time-dependent electric field for the first time. An analytical formula for calculating the time-dependent photodetachment cross section of this system has been put forward. It is found when the external electric field changes very slowly with time, there is only one closed orbit of the detached electron and the photodetachment cross section is quite stable. However, when the electric field changes quickly with time, three different types of closed orbits are found and the photodetachment cross section oscillates in a much more complex way. The connection of each type of closed orbit with the oscillatory structure in the photodetachment cross section is analyzed quantitatively. In addition, the photon energy and the laser field parameters can also have great influence on the time-dependent photodetachment cross section of this system. This study provides a clear and intuitive picture for the photodetachment dynamics of a negative ion in the presence of a time-dependent electric field and may guide future experimental studies exploring the quantum effect in the photodetachment dynamics of negative ions from a time-dependent viewpoint. (paper)

  11. Photodetachment of negative C{sub 60}{sup -} ions

    Energy Technology Data Exchange (ETDEWEB)

    Amusia, M.Ya.; Baltenkov, A.S.; Krakov, B.G. [Ioffe Physico-Technical Inst., St. Petersburg (Russian Federation)]|[U.A. Arifov Institute of Electronics, Tashkent, 700143 (Uzbekistan)

    1998-06-15

    A model that describes the electron structure of negative fullerene C{sub 60}{sup -} ions is proposed. The model contains only two experimentally observed parameters, namely the fullerene radius and the affinity energy of the electron to neutral C{sub 60}. In the frame of this model, cross sections are calculated of elastic scattering of slow electrons on neutral fullerene, of C{sub 60}{sup -} photodetachment near the threshold of this process and of radiative recombination of slow electrons with neutral fullerenes. (orig.) 21 refs.

  12. Photodetachment cross sections for He-(4P0)

    International Nuclear Information System (INIS)

    Compton, R.N.; Alton, G.D.; Pegg, D.J.

    1980-01-01

    The first measurements are reported of photodetachment cross sections for He - (formed through charge exchange of He + with Ca vapor) over the photon energy range from 1.77 to 2.75 eV. The energies of autodetached electrons from the metastable He - beam have also been determined for the first time. The autodetached electron energy agrees within experimental error (+-0.25 eV) with the known 1s2s2p) 4 P 0 He - energy level. This taken with measurements for the lifetime of He - infers that charge exchange of He + with Ca vapor produces 4 P 0 He -

  13. Negative-Ion source for mass selective photodetachment photoelectron spectroscopy

    International Nuclear Information System (INIS)

    Kaesmaier, R.; Baemann, C.; Drechsler, G.; Boesl, U.

    1995-01-01

    We have designed and constructed a negative ion source for mass spectrometry and mass selective photodetachement photoelectron spectroscopy. The characteristics of the source are high anion densities and a large variety of accessible systems. Thus, mass spectra and photoelectron spectra of large unvolatile moelcules (biomolecules), of metal-organic compounds and of molecule water clusters, especially mentioned in this article, have been measured. Combining mass spectrometry, photoelectron spectroscopy (PES) and high resolution ZEKE (zero kinetic energy)-PES (1) should make the apparatus to an ideal diagnostic tool for structural assignment

  14. Photodetachment spectroscopy and microscopy; measurement of the photodetachment cross section of H- at 1064 nm by the observation of the asymptotic behaviour in the saturated regime

    International Nuclear Information System (INIS)

    Vandevraye, Mickael

    2013-01-01

    In this thesis, we initiate the demonstration, at a reduced scale, of the feasibility of the almost-complete laser photodetachment of negative hydrogen ion beams in a Fabry-Perot optical cavity for future neutral beam injectors for the heating of fusion power plants plasmas.We develop a new method to measure a photodetachment cross section, the knowledge of which at the exciting wavelength is needed to scale the Fabry-Perot cavity, based on the observation of the saturation in a pulsed lighting regime. The analytical calculus of the detachment signal growth produced while illuminating a negative ion beam with a Gaussian laser pulse bring out a mathematical constraint on the required flux to pass through the saturated regime. This constraint is the signature of the transition toward the saturation for all experiment carried out in Gaussian beam and for all linear light-matter interaction processes. With this method, we measure the photodetachment cross section of H - at 1064 nm - selected wavelength for future neutral beam injectors - in slight disagreement with theoretical predictions.To reduce the technological requirement on the Fabry-Perot cavity and the laser, we study Landau resonances which appear in the photodetachment spectrum. Locking the laser on one of these resonances would allow increasing the photodetachment probability at a given flux.We also present our phosphorus, selenium and tin electron affinity measurements carried out with the photodetachment microscope. The photodetachment microscopy experiment of phosphorus is the first one where the neutral atom is left in an excited term. (author) [fr

  15. Photodetachment spectroscopy and microscopy, measurement of the photodetachment cross section of H- at 1064 nm by the observation of the asymptotic behaviour in the saturated regime

    International Nuclear Information System (INIS)

    Vandevraye, M.

    2013-01-01

    In this thesis, we initiate the demonstration, at a reduced scale, of the feasibility of the almost-complete laser photodetachment of negative hydrogen ion beams in a Fabry-Perot optical cavity for future neutral beam injectors for the heating of fusion power plants plasmas. We develop a new method to measure a photodetachment cross section, the knowledge of which at the exciting wavelength is needed to scale the Fabry-Perot cavity, based on the observation of the saturation in a pulsed lighting regime. The analytical calculus of the detachment signal growth produced while illuminating a negative ion beam with a Gaussian laser pulse bring out a mathematical constraint on the required flux to pass through the saturated regime. This constraint is the signature of the transition toward the saturation for all experiment carried out in Gaussian beam and for all linear light-matter interaction processes. With this method, we measure the photodetachment cross section of H - at 1064 nm - selected wavelength for future neutral beam injectors - we get 5.0*10 -21 m 2 in slight disagreement with theoretical predictions. To reduce the technological requirement on the Fabry-Perot cavity and the laser, we study Landau resonances which appear in the photodetachment spectrum. Locking the laser on one of these resonances would allow increasing the photodetachment probability at a given flux. We also present our phosphorus, selenium and tin electron affinity measurements carried out with the photodetachment microscope. We get the following values: 6021.81(8) cm -1 for P, 16297.276(9) cm -1 for Se and 8969.447(13) cm -1 . The photodetachment microscopy experiment of phosphorus is the first one where the neutral atom is left in an excited term. (author)

  16. Negative Ion Source Development and Photodetachment Studies at ISOLDE

    CERN Document Server

    AUTHOR|(CDS)2254068; Hanstorp, Dag; Rothe, Sebastian

    Astatine is one of the rarest elements on earth. The small amount of existing astatine is either created in decay chains of heavier elements or artificially. One of its longer lived isotopes, 211At, is of interest for targeted alpha therapy, a method of treating cancer by using the alpha decay of radioactive elements directly at the location of a tumor. However, its chemical properties are yet to be determined due to the short life time of astatine. A milestone towards the determination of the electronegativity of astatine was the measurement of its ionization potential (IP) at CERN-ISOLDE. However, its electron affinity (EA, the binding energy of the additional electron in a negative ion), is still to be measured. In order to determine the EA of radioisotopes by laser photodetachment spectroscopy, the Gothenburg ANion Detector for Affinity measurements by Laser Photodetachment (GANDALPH) has been built in recent years. As a proof-of-principle, the EA of the 128I negative ion, produced at the CERN-ISOLDE rad...

  17. K-shell photodetachment of the negative ion of beryllium

    International Nuclear Information System (INIS)

    Carlin, N M; Ramsbottom, C A; Bell, K L; Hibbert, A

    2003-01-01

    The partial and total cross sections for photodetachment of the metastable 1s 2 2s2p 2 4 P e bound state of the negative ion of beryllium are presented for a range of initial photon energies across and beyond the 1s detachment threshold. The cross sections are computed using a multichannel close-coupling R-matrix approximation, where sophisticated configuration-interaction wavefunctions are used to represent the initial and final states. Twelve target eigenstates with configurations 1s 2 2s2p, 1s 2 2p 2 , 1s2s 2 2p, 1s2s2p 2 and 1s2p 3 are included in the expansion of the total wavefunction describing the neutral Be atom. A number of prominent resonance structures have been identified in the partial cross sections for the three total system symmetry transitions of interest: 4 P e - 4 S o , 4 P o and 4 D o . No comparison can be made at this stage with other theoretical or experimental measurements due to a lack of data describing the inner shell photodetachment of the negative ion of beryllium

  18. Photodetachment of H- in the presence of a low-frequency laser field

    International Nuclear Information System (INIS)

    Bivona, S.; Burlon, R.; Leone, C.

    1992-01-01

    The photodetachment of a model one-electron ion simulating H - in the presence of a low-frequency field is analyzed. Two different geometries are considered in order to get information on the effect of the ponderomotive energy shift Δ on the photodetachment cross section. Our calculations suggest that a correspondence may be established between the ponderomotive shift and the photodetachment cross section, when the ejected electron may exchange only a few low-frequency photons. This is in qualitative agreement with recent experimental observations. When a large number of processes are open in which the detached electron may exchange low-frequency photons with comparable probability, it is impossible to make any connection between ponderomotive threshold shift and photodetachment cross section which, instead, may be described in terms of a field picture

  19. Shape resonance in K-shell photodetachment from C-

    International Nuclear Information System (INIS)

    Walter, C. W.; Gibson, N. D.; Bilodeau, R. C.; Berrah, N.; Bozek, J. D.; Ackerman, G. D.; Aguilar, A.

    2006-01-01

    The core-excited (1s2s 2 2p 4 4 P) negative ion shape resonance of C - near 281.7 eV has been investigated using the merged ion beam--photon beam photodetachment technique on the Advanced Light Source beamline 10.0.1. C + ions formed by double detachment were detected as a function of photon energy. Higher resolution spectra yield more precise values for the energy and width of the resonance than our previous measurements [N. D. Gibson et al., Phys. Rev. A 67, 030703(R) (2003)]. The absolute cross section for double detachment from C - following 1s photoexcitation is measured for the first time and the spectrum is compared to previous theoretical calculations. These measurements also provide information on the lowest core-excited state of neutral carbon (1s2s 2 2p 3 5 S)

  20. Influence of the oscillating electric field on the photodetachment of H− ion in a static electric field

    International Nuclear Information System (INIS)

    Wang, De-hua

    2017-01-01

    Highlights: • The photodetachment of H − in an oscillating electric field has been studied using the time-dependent closed orbit theory. • An analytical formula for calculating the photodetachement cross section has been put forward. • Our study provides a clear physical picture for the photodetachment of negative ion in an oscillating electric filed. • Our work is useful in guiding the experimental research for the photodetachment dynamics in the time-dependent field. - Abstract: Using the time-dependent closed orbit theory, we study the photodetachment of H − ion in a time-dependent electric field. The photodetachment cross section is specifically studied in the presence of a static electric field plus an oscillating electric field. We find that the photodetachment of negative ion in the time-dependent electric field becomes much more complicated than the case in a static electric field. The oscillating electric field can weaken the photodetachment cross section greatly when the strength of the oscillating electric field is less than the static electric field. However, as the strength of the oscillating electric field is larger than the static electric field, four types of closed orbits are identified for the detached electron, which makes the oscillating amplitude in the photodetachment cross section gets increased again. The connection between the detached electron’s closed orbit with the oscillating cross section is analyzed quantitatively. This study provides a clear and intuitive picture for the understanding of the connections between quantum and classical description for the time-dependent Hamiltonian systems and may guide the future experimental research for the photodetachment dynamics in the time-dependent electric field.

  1. Laser photodetachment of radioactive ions: towards the determination of the electronegativity of astatine

    CERN Multimedia

    Rothe, Sebastian; Welander, Jakob Emanuel; Chrysalidis, Katerina; Day Goodacre, Thomas; Fedosseev, Valentine; Fiotakis, Spyridon; Forstner, Oliver; Heinke, Reinhard Matthias; Johnston, Karl; Kron, Tobias; Koester, Ulli; Liu, Yuan; Marsh, Bruce; Ringvall Moberg, Annie; Rossel, Ralf Erik; Seiffert, Christoph; Studer, Dominik; Wendt, Klaus; Hanstorp, Dag

    2017-01-01

    Negatively charged ions are mainly stabilized through the electron correlation effect. A measure of the stability of a negative ion is the electron affinity, which the energy gain by attaching an electron to a neutral atom. This fundamental quantity is, due to the almost general lack of bound excited states, the only atomic property that can be determined with high accuracy for negative ions. We will present the results of the first laser photodetachment studies of radioactive negative ions at CERN-ISOLDE. The photodetachment threshold for the radiogenic iodine isotope 128I was measured successfully, demonstrating the performance of the upgraded GANDALPH experimental beam line. The first detection of photo-detached astatine atoms marks a milestone towards the determination of the EA of this radioactive element.

  2. Mechanisms mediating vibration-induced chronic musculoskeletal pain analyzed in the rat.

    Science.gov (United States)

    Dina, Olayinka A; Joseph, Elizabeth K; Levine, Jon D; Green, Paul G

    2010-04-01

    While occupational exposure to vibration is a common cause of acute and chronic musculoskeletal pain, eliminating exposure produces limited symptomatic improvement, and reexposure precipitates rapid recurrence or exacerbation. To evaluate mechanisms underlying these pain syndromes, we have developed a model in the rat, in which exposure to vibration (60-80Hz) induces, in skeletal muscle, both acute mechanical hyperalgesia as well as long-term changes characterized by enhanced hyperalgesia to a proinflammatory cytokine or reexposure to vibration. Exposure of a hind limb to vibration-produced mechanical hyperalgesia measured in the gastrocnemius muscle of the exposed hind limb, which persisted for approximately 2 weeks. When nociceptive thresholds had returned to baseline, exposure to a proinflammatory cytokine or reexposure to vibration produced markedly prolonged hyperalgesia. The chronic prolongation of vibration- and cytokine-hyperalgesia was prevented by spinal intrathecal injection of oligodeoxynucleotide (ODN) antisense to protein kinase Cepsilon, a second messenger in nociceptors implicated in the induction and maintenance of chronic pain. Vibration-induced hyperalgesia was inhibited by spinal intrathecal administration of ODN antisense to receptors for the type-1 tumor necrosis factor-alpha (TNFalpha) receptor. Finally, in TNFalpha-pretreated muscle, subsequent vibration-induced hyperalgesia was markedly prolonged. These studies establish a model of vibration-induced acute and chronic musculoskeletal pain, and identify the proinflammatory cytokine TNFalpha and the second messenger protein kinase Cepsilon as targets against which therapies might be directed to prevent and/or treat this common and very debilitating chronic pain syndrome. Copyright 2010 American Pain Society. All rights reserved.

  3. The Effects of Spherical Surface and Laser Polarization on the Photodetachment Cross Section of H−

    International Nuclear Information System (INIS)

    Haneef Muhammad; Arif Suneela; Akbar Jehan; Shamim Aneela; Shah Nasrullah; Zahir Muhammad; Ullah Hameed

    2013-01-01

    We report the combined effects of laser polarization and curvature of the spherical surface on the detached electron spectra from H − . The Theoretical imaging method is used as a tool of investigation. The photodetachment cross sections for various polarization angles, radii of curvatures and inter ion surface distances are displayed. The analysis of the spectra reveals that the laser polarization angle θ L , curvature of the surface r c and inter ion surface distance d strongly affect oscillations in the spectra. Therefore, a fine control on the laser polarization and that of curvature in the surface can be used to control oscillations in the photodetachment of negative ions. (atomic and molecular physics)

  4. Mechanisms Mediating Vibration-induced Chronic Musculoskeletal Pain Analyzed in the Rat

    OpenAIRE

    Dina, Olayinka A.; Joseph, Elizabeth K.; Levine, Jon D.; Green, Paul G.

    2009-01-01

    While occupational exposure to vibration is a common cause of acute and chronic musculoskeletal pain, eliminating exposure produces limited symptomatic improvement, and re-exposure precipitates rapid recurrence or exacerbation. To evaluate mechanisms underlying these pain syndromes, we have developed a model in the rat, in which exposure to vibration (60–80 Hz) induces, in skeletal muscle, both acute mechanical hyperalgesia as well as long-term changes characterized by enhanced hyperalgesia t...

  5. Photodetachment electron flux of H− in combined electric and magnetic fields with arbitrary orientation

    International Nuclear Information System (INIS)

    Wang, De-hua

    2013-01-01

    Highlights: •On the basis of the semiclassical theory, the photodetachment electron flux of H − in combined electric field and magnetic field with arbitrary orientation has been studied for the first time. •Our calculation results suggest that the electron flux distributions on the detector plane is not only related to the angle between the electric and magnetic fields, but also related to the electron energy. •Our studies may guide the future experimental researches in the photodetachment microscopy of some more complex negative ions in the presence of external fields. -- Abstract: On the basis of the semi-classical theory, we calculate the photodetachment electron flux of H − in combined electric field and magnetic field with arbitrary orientation. Our results suggest that the electron flux distributions on the detector plane is not only related to the angle between the electric and magnetic fields, but also related to the electron energy. With the increase of the angle between the electric and magnetic field, the oscillating region in the electron flux distributions becomes smaller. In addition, we find with the increase of the detached electron's energy, the oscillating structure in the flux distributions becomes much more complicated. Therefore, the oscillation in the detached electron flux distributions can be controlled by adjusting the angle between the electric and magnetic field and the detached electron's energy. We hope that our studies may guide the future experimental researches in the photodetachment microscopy of negative ion in the presence of external fields

  6. Aharonov-Bohm Effect in the Photodetachment Microscopy of Hydrogen Negative Ions in an Electric Field

    Science.gov (United States)

    Wang, Dehua

    2014-09-01

    The Aharonov-Bohm (AB) effect in the photodetachment microscopy of the H- ions in an electric field has been studied on the basis of the semiclassical theory. After the H- ion is irradiated by a laser light, they provide a coherent electron source. When the detached electron is accelerated by a uniform electric field, two trajectories of a detached electron which run from the source to the same point on the detector, will interfere with each other and lead to an interference pattern in the photodetachment microscopy. After the solenoid is electrified beside the H- ion, even though no Lorentz force acts on the electron outside the solenoid, the photodetachment microscopy interference pattern on the detector is changed with the variation in the magnetic flux enclosed by the solenoid. This is caused by the AB effect. Under certain conditions, the interference pattern reaches the macroscopic dimensions and could be observed in a direct AB effect experiment. Our study can provide some predictions for the future experimental study of the AB effect in the photodetachment microscopy of negative ions.

  7. Vibrot, a simple device for the conversion of vibration into rotation mediated by friction: preliminary evaluation.

    Directory of Open Access Journals (Sweden)

    Ernesto Altshuler

    Full Text Available While "vibrational noise" induced by rotating components of machinery is a common problem constantly faced by engineers, the controlled conversion of translational into rotational motion or vice-versa is a desirable goal in many scenarios ranging from internal combustion engines to ultrasonic motors. In this work, we describe the underlying physics after isolating a single degree of freedom, focusing on devices that convert a vibration along the vertical axis into a rotation around this axis. A typical Vibrot (as we label these devices consists of a rigid body with three or more cantilevered elastic legs attached to its bottom at an angle. We show that these legs are capable of transforming vibration into rotation by a "ratchet effect", which is caused by the anisotropic stick-slip-flight motion of the leg tips against the ground. Drawing an analogy with the Froude number used to classify the locomotion dynamics of legged animals, we discuss the walking regime of these robots. We are able to control the rotation frequency of the Vibrot by manipulating the shaking amplitude, frequency or waveform. Furthermore, we have been able to excite Vibrots with acoustic waves, which allows speculating about the possibility of reducing the size of the devices so they can perform tasks into the human body, excited by ultrasound waves from the outside.

  8. Semiochemical and Vibrational Cues and Signals Mediating Mate Finding and Courtship in Psylloidea (Hemiptera: A Synthesis

    Directory of Open Access Journals (Sweden)

    Umar K. Lubanga

    2014-07-01

    Full Text Available Mate finding and courtship involve complex interactions that require close coordination between individuals of the opposite gender. Well-organized signalling systems, sometimes involving a combination of signal modalities, are required to convey species-specific and individual information to members of the opposite gender. Previous studies of psyllids have focused on single-signal modalities and have largely ignored the potentially interdependent nature of different types of signals. Several studies have shown that semiochemicals play a role in psyllid mate finding. However, long-range semiochemical sex attractants, such as the highly volatile sex pheromones used by many Lepidoptera (molecular weights <300, are yet to be identified. The compounds identified thus far, namely 13-methylheptacosane (from Cacopsylla pyricola and dodecanoic acid (from Diaphorina citri, seem to have short range activity or no activity under field conditions. The possible role played by cuticular hydrocarbons in psyllid courtship remains largely ignored. Conversely, many psyllid species rely on vibrational signals for mate finding and mate assessment during courtship. This apparent disproportional reliance on vibrational rather than semiochemical signals suggests that vibrational signals have been more influential in sexual selection in psyllids. However, male fitness, female choice and benefits accrued from selecting fitter males remain poorly understood.

  9. Effects of electric fields on the photodetachment cross section of the H- ion near threshold

    International Nuclear Information System (INIS)

    Stewart, J.E.

    1987-12-01

    The photodetachment cross section of the H - ion near the one electron threshold in electric fields ranging from approximately 5 x 10 -7 atomic units up to 2.4 x 10 -4 atomic units has been studied using an 800 MeV beam at the Los Alamos National Laboratory. The lowest field data, analyzed as though at zero field, are consistent with the Wigner prediction for p wave processes. At greater field values, photodetachment using σ polarized laser light displays the expected lowering of apparent threshold and evidence of tunneling. Using π polarized laser light the same features are seen with the addition of oscillations superimposed on the cross section. Three complementary explanations are presented for the oscillations. 42 refs., 35 figs., 8 tabs

  10. Determination of the electron affinity of astatine and polonium by laser photodetachment

    CERN Multimedia

    We propose to conduct the first electron affinity (EA) measurements of the two elements astatine (At) and polonium (Po). Collinear photo-detachment spectroscopy will allow us to measure these quantities with an uncertainty limited only by the spectral line width of the laser. We plan to use negative ion beams of the two radioactive elements At and Po, which are only accessible on-line and at ISOLDE. The feasibility of our proposed method and the functionality of the experimental setup have been demonstrated at ISOLDE in off-line tests by the clear observation of the photo-detachment threshold for stable iodine. This proposal is based on our Letter of Intent I-148.

  11. Dynamics of gas-phase transient species studied by dissociative photodetachment of molecular anions

    OpenAIRE

    Lu, Zhou

    2007-01-01

    Gas-phase transient species, such as the CH₃CO₂ and HOCO free radicals, play important roles in combustion and environment chemistry. In this thesis work, the dynamics of these two radicals were studied by dissociative photodetachment (DPD) of the negative ions, CH₃CO₂-С and HOCO⁻, respectively. The experiments were carried out with a fast-ion-beam photoelectron-photofragment coincidence (PPC) spectrometer. Mass-selected molecular anions in a fast ion beam were intercepted by a linearly polar...

  12. Approaching the O{sup -} photodetachment threshold with velocity-map imaging

    Energy Technology Data Exchange (ETDEWEB)

    Cavanagh, S J; Gibson, S T; Lewis, B R, E-mail: Steven.Cavanagh@anu.edu.a, E-mail: Stephen.Gibson@anu.edu.a [Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia)

    2009-11-01

    A series of photodetachment spectra from O{sup -} has been measured from near threshold to several eV using the technique of velocity-map imaging. With a resolving power of {Delta}E/E {<=} 0.38%, the energy and angular dependences for the six fine-structure transitions have been determined. For the first time, the energy and angular dependences of the cross section within a few meV of threshold have been determined.

  13. A coupled-cluster study of photodetachment cross sections of closed-shell anions

    Science.gov (United States)

    Cukras, Janusz; Decleva, Piero; Coriani, Sonia

    2014-11-01

    We investigate the performance of Stieltjes Imaging applied to Lanczos pseudo-spectra generated at the coupled cluster singles and doubles, coupled cluster singles and approximate iterative doubles and coupled cluster singles levels of theory in modeling the photodetachment cross sections of the closed shell anions H-, Li-, Na-, F-, Cl-, and OH-. The accurate description of double excitations is found to play a much more important role than in the case of photoionization of neutral species.

  14. A coupled-cluster study of photodetachment cross sections of closed-shell anions

    International Nuclear Information System (INIS)

    Cukras, Janusz; Decleva, Piero; Coriani, Sonia

    2014-01-01

    We investigate the performance of Stieltjes Imaging applied to Lanczos pseudo-spectra generated at the coupled cluster singles and doubles, coupled cluster singles and approximate iterative doubles and coupled cluster singles levels of theory in modeling the photodetachment cross sections of the closed shell anions H − , Li − , Na − , F − , Cl − , and OH − . The accurate description of double excitations is found to play a much more important role than in the case of photoionization of neutral species

  15. Photodetachment of H- by a short laser pulse in crossed static electric and magnetic fields

    International Nuclear Information System (INIS)

    Peng Liangyou; Wang Qiaoling; Starace, Anthony F.

    2006-01-01

    We present a detailed quantum mechanical treatment of the photodetachment of H - by a short laser pulse in the presence of crossed static electric and magnetic fields. An exact analytic formula is presented for the final state electron wave function (describing an electron in both static electric and magnetic fields and a short laser pulse of arbitrary intensity). In the limit of a weak laser pulse, final state electron wave packet motion is examined and related to the closed classical electron orbits in crossed static fields predicted by Peters and Delos [Phys. Rev. A 47, 3020 (1993)]. Owing to these closed orbit trajectories, we show that the detachment probability can be modulated, depending on the time delay between two laser pulses and their relative phase, thereby providing a means to partially control the photodetachment process. In the limit of a long, weak pulse (i.e., a monochromatic radiation field) our results reduce to those of others; however, for this case we analyze the photodetachment cross section numerically over a much larger range of electron kinetic energy (i.e., up to 500 cm -1 ) than in previous studies and relate the detailed structures both analytically and numerically to the above-mentioned, closed classical periodic orbits

  16. Measurements of threshold behavior for one- and two-electron photodetachment from the H- ion

    International Nuclear Information System (INIS)

    Frost, C.A.

    1981-09-01

    One and two-electron photodetachment from the H - ion by a single photon has been studied using a crossed beam apparatus. A Q-switched laser beam was directed across the 800 MeV H - beam at LAMPF (β=0.842) resulting in Doppler-shifted photon energies in the H - barycentric frame, which were tunable from 0.4 eV to 15.5 eV by changing the intersection angle. The particles (e - , H 0 , H + ) resulting from photodetachment reactions were magnetically deflected into scintillation detectors allowing the total and partial cross sections for 1e - and 2e - processes to be separately measured. The 2e - signal (H + ) was produced by two different mechanisms, the true signal γ + H - → H + + 2e - and the background process γ + H - → H 0 (n), followed by motional electric field ionization of excited H 0 . Two-electron photodetachment which had been predicted theoretically was observed for the first time, and the relative cross section was measured from threshold to 15.5 eV. Tfrared absorption spectra of intrinsic a-Si:H films by the argon working gas partial pressure, hydrogen partial pressure, and substrate temperature variperiods of time at lower temperatures because aromatic hydrocarbons economic conditions. The symptomology of the various trace metals and oxides isen as potentially more efficient for both employer and employee than is the use of regulatory standards

  17. Communication: On the competition between adiabatic and nonadiabatic dynamics in vibrationally mediated ammonia photodissociation in its A band

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Changjian [Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Institute of Theoretical and Computational Chemistry, Nanjing University, Nanjing 210093 (China); Zhu, Xiaolei; Yarkony, David R., E-mail: jianyi.m@gmail.com, E-mail: yarkony@jhu.edu, E-mail: dqxie@nju.edu.cn, E-mail: hguo@unm.edu [Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Ma, Jianyi, E-mail: jianyi.m@gmail.com, E-mail: yarkony@jhu.edu, E-mail: dqxie@nju.edu.cn, E-mail: hguo@unm.edu [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, Sichuan 610065 (China); Xie, Daiqian, E-mail: jianyi.m@gmail.com, E-mail: yarkony@jhu.edu, E-mail: dqxie@nju.edu.cn, E-mail: hguo@unm.edu [Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Institute of Theoretical and Computational Chemistry, Nanjing University, Nanjing 210093 (China); Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Guo, Hua, E-mail: jianyi.m@gmail.com, E-mail: yarkony@jhu.edu, E-mail: dqxie@nju.edu.cn, E-mail: hguo@unm.edu [Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131 (United States)

    2015-03-07

    Non-adiabatic processes play an important role in photochemistry, but the mechanism for conversion of electronic energy to chemical energy is still poorly understood. To explore the possibility of vibrational control of non-adiabatic dynamics in a prototypical photoreaction, namely, the A-band photodissociation of NH{sub 3}(X{sup ~1}A{sub 1}), full-dimensional state-to-state quantum dynamics of symmetric or antisymmetric stretch excited NH{sub 3}(X{sup ~1}A{sub 1}) is investigated on recently developed coupled diabatic potential energy surfaces. The experimentally observed H atom kinetic energy distributions are reproduced. However, contrary to previous inferences, the NH{sub 2}(A{sup ~2}A{sub 1})/NH{sub 2}(X{sup ~2}B{sub 1}) branching ratio is found to be small regardless of the initial preparation of NH{sub 3}(X{sup ~1}A{sub 1}), while the internal state distribution of the preeminent fragment, NH{sub 2}(X{sup ~2}B{sub 1}), is found to depend strongly on the initial vibrational excitation of NH{sub 3}(X{sup ~1}A{sub 1}). The slow H atoms in photodissociation mediated by the antisymmetric stretch fundamental state are due to energy sequestered in the internally excited NH{sub 2}(X{sup ~2}B{sub 1}) fragment, rather than in NH{sub 2}(A{sup ~2}A{sub 1}) as previously proposed. The high internal excitation of the NH{sub 2}(X{sup ~2}B{sub 1}) fragment is attributed to the torques exerted on the molecule as it passes through the conical intersection seam to the ground electronic state of NH{sub 3}. Thus in this system, contrary to previous assertions, the control of electronic state branching by selective excitation of ground state vibrational modes is concluded to be ineffective. The juxtaposition of precise quantum mechanical results with complementary results based on quasi-classical surface hopping trajectories provides significant insights into the non-adiabatic process.

  18. Numerical experiment to estimate the validity of negative ion diagnostic using photo-detachment combined with Langmuir probing

    Energy Technology Data Exchange (ETDEWEB)

    Oudini, N. [Laboratoire des plasmas de décharges, Centre de Développement des Technologies Avancées, Cité du 20 Aout BP 17 Baba Hassen, 16081 Algiers (Algeria); Sirse, N.; Ellingboe, A. R. [Plasma Research Laboratory, School of Physical Sciences and NCPST, Dublin City University, Dublin 9 (Ireland); Benallal, R. [Unité de Recherche Matériaux et Energies Renouvelables, BP 119, Université Abou Bekr Belkaïd, Tlemcen 13000 (Algeria); Taccogna, F. [Istituto di Metodologie Inorganiche e di Plasmi, CNR, via Amendola 122/D, 70126 Bari (Italy); Aanesland, A. [Laboratoire de Physique des Plasmas, (CNRS, Ecole Polytechnique, Sorbonne Universités, UPMC Univ Paris 06, Univ Paris-Sud), École Polytechnique, 91128 Palaiseau Cedex (France); Bendib, A. [Laboratoire d' Electronique Quantique, Faculté de Physique, USTHB, El Alia BP 32, Bab Ezzouar, 16111 Algiers (Algeria)

    2015-07-15

    This paper presents a critical assessment of the theory of photo-detachment diagnostic method used to probe the negative ion density and electronegativity α = n{sub -}/n{sub e}. In this method, a laser pulse is used to photo-detach all negative ions located within the electropositive channel (laser spot region). The negative ion density is estimated based on the assumption that the increase of the current collected by an electrostatic probe biased positively to the plasma is a result of only the creation of photo-detached electrons. In parallel, the background electron density and temperature are considered as constants during this diagnostics. While the numerical experiments performed here show that the background electron density and temperature increase due to the formation of an electrostatic potential barrier around the electropositive channel. The time scale of potential barrier rise is about 2 ns, which is comparable to the time required to completely photo-detach the negative ions in the electropositive channel (∼3 ns). We find that neglecting the effect of the potential barrier on the background plasma leads to an erroneous determination of the negative ion density. Moreover, the background electron velocity distribution function within the electropositive channel is not Maxwellian. This is due to the acceleration of these electrons through the electrostatic potential barrier. In this work, the validity of the photo-detachment diagnostic assumptions is questioned and our results illustrate the weakness of these assumptions.

  19. Study of small carbon and semiconductor clusters using negative ion threshold photodetachment spectroscopy

    International Nuclear Information System (INIS)

    Arnold, C.C.

    1994-08-01

    The bonding and electronics of several small carbon and semiconductor clusters containing less than ten atoms are probed using negative ion threshold photodetachment (zero electron kinetic energy, or ZEKE) spectroscopy. ZEKE spectroscopy is a particularly advantageous technique for small cluster study, as it combines mass selection with good spectroscopic resolution. The ground and low-lying electronic states of small clusters in general can be accessed by detaching an electron from the ground anion state. The clusters studied using this technique and described in this work are C 6 - /C 6 , Si n - /Si n (n = 2, 3, 4), Ge 2 - /Ge 2 , In 2 P - /In 2 P,InP 2 - /InP 2 , and Ga 2 As - . The total photodetachment cross sections of several other small carbon clusters and the ZEKE spectrum of the I - ·CH 3 I S N 2 reaction complex are also presented to illustrate the versatility of the experimental apparatus. Clusters with so few atoms do not exhibit bulk properties. However, each specie exhibits bonding properties that relate to the type of bonding found in the bulk. C 6 , as has been predicted, exhibits a linear cumulenic structure, where double bonds connect all six carbon atoms. This double bonding reflects how important π bonding is in certain phases of pure carbon (graphite and fullerenes). The symmetric stretch frequencies observed in the C 6 - spectra, however, are in poor agreement with the calculated values. Also observed as sharp structure in total photodetachment cross section scans was an excited anion state bound by only ∼40 cm -1 relative to the detachment continuum. This excited anion state appears to be a valence bound state, possible because of the high electron affinity of C 6 , and the open shell of the anion

  20. Rotationally resolved photodetachment spectrum of OH{sup -}, exposed with velocity-map imaging

    Energy Technology Data Exchange (ETDEWEB)

    Gibson, S T; Cavanagh, S J; Lewis, B R, E-mail: Stephen.Gibson@anu.edu.a, E-mail: Steven.Cavanagh@anu.edu.a [Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia)

    2009-11-01

    The photodetachment spectrum of OH{sup -} has been measured using velocity-map imaging for the detection of photoelectrons. The relative electron kinetic-energy resolution, determined to be ({Delta}E/E) = 0.5%, resolves individual rotational transitions, including R3(0) that defines the electron affinity. Previously unobserved, N-, O-, S-, T-branch transitions are also revealed. The angular anisotropy parameters in general exhibit values consistent with electron detachment from O{sup -}, {beta} {approx} -0.8, except for the S, T branches which are significantly more isotropic, with {beta} {approx} -0.4.

  1. Mirroring behavior of partial photodetachment and photoionization cross sections in the neighborhood of a resonance

    International Nuclear Information System (INIS)

    Liu, C.; Starace, A.F.

    1999-01-01

    Partial photodetachment and photoionization cross sections corresponding to highly excited residual atoms or ions are shown analytically to mirror one another in the neighborhood of a resonance. More precisely, any two groupings of partial cross sections are shown here to have components whose variations with energy near a resonance are equal in magnitude and opposite in direction. This work extends an analysis of Starace [Phys. Rev. A 16, 231 (1977)] for the behavior of partial cross sections near a resonance to the case when the ρ 2 parameter of Fano and Cooper [Phys. Rev. 137, A1364 (1965)] tends to zero. copyright 1999 The American Physical Society

  2. Mirroring behavior of partial photodetachment and photoionization cross sections in the neighborhood of a resonance

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.; Starace, A.F. [Department of Physics and Astronomy, The University of Nebraska, Lincoln, Nebraska 68588-0111 (United States)

    1999-03-01

    Partial photodetachment and photoionization cross sections corresponding to highly excited residual atoms or ions are shown analytically to mirror one another in the neighborhood of a resonance. More precisely, any two groupings of partial cross sections are shown here to have components whose variations with energy near a resonance are equal in magnitude and opposite in direction. This work extends an analysis of Starace [Phys. Rev. A {bold 16}, 231 (1977)] for the behavior of partial cross sections near a resonance to the case when the {rho}{sup 2} parameter of Fano and Cooper [Phys. Rev. {bold 137}, A1364 (1965)] tends to zero. {copyright} {ital 1999} {ital The American Physical Society}

  3. A coupled-cluster study of photodetachment cross sections of closed-shell anions

    Energy Technology Data Exchange (ETDEWEB)

    Cukras, Janusz; Decleva, Piero; Coriani, Sonia, E-mail: coriani@units.it [Dipartimento di Scienze Chimiche e Farmaceutiche, Università degli Studi di Trieste, via L. Giorgieri 1, I-34127, Trieste (Italy)

    2014-11-07

    We investigate the performance of Stieltjes Imaging applied to Lanczos pseudo-spectra generated at the coupled cluster singles and doubles, coupled cluster singles and approximate iterative doubles and coupled cluster singles levels of theory in modeling the photodetachment cross sections of the closed shell anions H{sup −}, Li{sup −}, Na{sup −}, F{sup −}, Cl{sup −}, and OH{sup −}. The accurate description of double excitations is found to play a much more important role than in the case of photoionization of neutral species.

  4. Experimental and Theoretical Studies of the F + H–F Transition-State Region by Photodetachment of [F–H–F] -

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Gao-Lei [Physical; Wang, Xue-Bin [Physical; McCoy, Anne B. [Department; Borden, Weston Thatcher [Department

    2017-10-05

    The transition-state (TS) region of the simplest heavy-light-heavy type of reaction, F• + H-F F-H + F•, is investigated in this work by a joint experimental and theoretical approach. Photodetaching the bifluride anion, [F…H…F]–, generates a negative ion photoelectron (NIPE) spectrum with three partially resolved bands in the electron binding energy (eBE) range of 5.4 – 7.0 eV. These bands correspond to the transition from the ground state of the anion to the electronic ground state of [F-H-F]• neutral, with associated vibrational excitations. The significant increase of eBE of the bifluride anion, relative to that of F-, reflects a hydrogen bond energy between F- and HF of 46 kcal/mol. Theoretical modeling reveals that the antisymmetric motion of H between the two F atoms, near the TS on the neutral [F-H-F]• surface, dominates the observed three bands, while the F-H-F bending, F—F symmetric stretching modes, and the couplings between them is calculated to account for the breadth of the observed spectrum. From the NIPE spectrum, a lower limit on the activation enthalpy for F• + H-F F-H + F can be estimated to be H‡ = 12 ± 2 kcal/mol, a value below that of H‡ = 14.9 kcal/mol, given by our G4 calculations.

  5. Electronegative plasma diagnostic by laser photo-detachment combined with negatively biased Langmuir probe

    Science.gov (United States)

    Oudini, N.; Sirse, N.; Taccogna, F.; Ellingboe, A. R.; Bendib, A.

    2018-05-01

    We propose a new technique for diagnosing negative ion properties using Langmuir probe assisted pulsed laser photo-detachment. While the classical technique uses a laser pulse to convert negative ions into electron-atom pairs and a positively biased Langmuir probe tracking the change of electron saturation current, the proposed method uses a negatively biased Langmuir probe to track the temporal evolution of positive ion current. The negative bias aims to avoid the parasitic electron current inherent to probe tip surface ablation. In this work, we show through analytical and numerical approaches that, by knowing electron temperature and performing photo-detachment at two different laser wavelengths, it is possible to deduce plasma electronegativity (ratio of negative ion to electron densities) α, and anisothermicity (ratio of electron to negative ion temperatures) γ-. We present an analytical model that links the change in the collected positive ion current to plasma electronegativity and anisothermicity. Particle-In-Cell simulation is used as a numerical experiment covering a wide range of α and γ- to test the new analysis technique. The new technique is sensitive to α in the range 0.5 1.

  6. 2008 Photoions, Photoionization & Photodetachment Gordon Research Conference January 27-February 1, 2008

    Energy Technology Data Exchange (ETDEWEB)

    Klaus Muller-Dethefs

    2009-03-31

    This conference brings together scientists interested in a range of basic phenomena linked to the ejection and scattering of electrons from atoms, molecules, clusters, liquids and solids by absorption of light. Photoionization, a highly sensitive probe of both structure and dynamics, can range from perturbative single-photon processes to strong-field highly non-perturbative interactions. It is responsible for the formation and destruction of molecules in astrophysical and plasma environments and successfully used in advanced analytical techniques. Positive ions, which can be produced and studied most effectively using photoionization, are the major components of all plasmas, vital constituents of flames and important intermediates in many chemical reactions. Negative ions are significant as transient species and, when photodetached, the corresponding neutral species often undergoes remarkable, otherwise non-observable, dynamics. The scope of the meeting spans from novel observations in atomic and molecular physics, such as Coulomb Crystals, highly excited states and cold Rydberg plasmas, to novel energy resolved or ultrafast time-resolved experiments, photoionization in strong laser fields, theoretical method development for electron scattering, photoionization and photodetachment and more complex phenomena such as charge transfer and DNA and protein conductivity, important for biological and analytical applications.

  7. Study of small carbon and semiconductor clusters using negative ion threshold photodetachment spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, Caroline Chick [Univ. of California, Berkeley, CA (United States)

    1994-08-01

    The bonding and electronics of several small carbon and semiconductor clusters containing less than ten atoms are probed using negative ion threshold photodetachment (zero electron kinetic energy, or ZEKE) spectroscopy. ZEKE spectroscopy is a particularly advantageous technique for small cluster study, as it combines mass selection with good spectroscopic resolution. The ground and low-lying electronic states of small clusters in general can be accessed by detaching an electron from the ground anion state. The clusters studied using this technique and described in this work are C6-/C6, Sin-/Sin (n = 2, 3, 4), Ge2-/Ge2, In2P-/In2P,InP2-/InP2, and Ga2As-. The total photodetachment cross sections of several other small carbon clusters and the ZEKE spectrum of the I-•CH3I SN2 reaction complex are also presented to illustrate the versatility of the experimental apparatus. Clusters with so few atoms do not exhibit bulk properties. However, each specie exhibits bonding properties that relate to the type of bonding found in the bulk. C6, as has been predicted, exhibits a linear cumulenic structure, where double bonds connect all six carbon atoms. This double bonding reflects how important π bonding is in certain phases of pure carbon (graphite and fullerenes). The symmetric stretch frequencies observed in the C6- spectra, however, are in poor agreement with the calculated values. Also observed as sharp structure in total photodetachment cross section scans was an excited anion state bound by only ~40 cm-1 relative to the detachment continuum. This excited anion state appears to be a valence bound state, possible because of the high electron affinity of C6, and the open shell of the anion.

  8. Negative ions of p-nitroaniline: Photodetachment, collisions, and ab initio calculations

    Science.gov (United States)

    Smith, Byron H.; Buonaugurio, Angela; Chen, Jing; Collins, Evan; Bowen, Kit H.; Compton, Robert N.; Sommerfeld, Thomas

    2013-06-01

    The structures of parent anion, M-, and deprotonated molecule, [M-H]-, anions of the highly polar p-nitroaniline (pNA) molecule are studied experimentally and theoretically. Photoelectron spectroscopy (PES) of the parent anion is employed to estimate the adiabatic electron affinity (EAa = 0.75 ± 0.1 eV) and vertical detachment energy (VDE = 1.1 eV). These measured energies are in good agreement with computed values of 0.73 eV for the EAa and the range of 0.85 to 1.0 eV for the VDE at the EOM-CCSD/Aug-cc-pVTZ level. Collision induced dissociation (CID) of deprotonated pNA, [pNA - H]-, with argon yielded [pNA - H - NO]- (i.e., rearrangement to give loss of NO) with a threshold energy of 2.36 eV. Calculations of the energy difference between [pNA - H]- and [pNA - H - NO]- give 1.64 eV, allowing an estimate of a 0.72 eV activation barrier for the rearrangement reaction. Direct dissociation of [pNA - H]- yielding NO_2^ - occurs at a threshold energy of 3.80 eV, in good agreement with theory (between 3.39 eV and 4.30 eV). As a result of the exceedingly large dipole moment for pNA (6.2 Debye measured in acetone), we predict two dipole-bound states, one at ˜110 meV and an excited state at 2 meV. No dipole-bound states are observed in the photodetachment experiments due the pronounced mixing between states with dipole-bound and valence character similar to what has been observed in other nitro systems. For the same reason, dipole-bound states are expected to provide highly efficient "doorway states" for the formation of the pNA- valence anion, and these states should be observable as resonances in the reverse process, that is, in the photodetachment spectrum of pNA- near the photodetachment threshold.

  9. Iodide- and bromide-specific electron-capture/photodetachment-modulated detector for the trace analysis of halocarbon mixtures

    International Nuclear Information System (INIS)

    Mock, R.S.; Grimsrud, E.P.

    1988-01-01

    The use of photodetachment (PD) of electrons from negative ions in a pulsed electron capture detector (ECD) is described. By passing a chopped light beam through the ECD and amplification of the modulated component of the ECD signal, the photodetachment-modulated (PDM) pulsed ECD can be made to respond selectively and sensitively to iodine- containing hydrocarbons alone, or to iodine- and bromine-containing hydrocarbons in the presence of chlorinated hydrocarbons. The detection limit of the iodide/bromide-specific mode of the PDM-ECD to CH 3 I is shown to be competitive with that of the normal mode of the pulsed ECD. This detection mode of the ECD is shown to be of great assistance in the gas chromatographic analysis of organobromides and organoiodides in complex mixtures which contain a large number of organochlorides

  10. Numerical simulations used for a validity check on the laser induced photo-detachment diagnostic method in electronegative plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Oudini, N. [Laboratoire des plasmas de décharges, Centre de Développement des Technologies Avancées, Cité du 20 Aout BP 17 Baba Hassen, 16081 Algiers (Algeria); Taccogna, F. [Istituto di Metodologie Inorganiche e dei Plasmi, CNR, via Amendola 122/D, 70126 Bari (Italy); Bendib, A. [Laboratoire d' Electronique Quantique, Faculté de Physique, USTHB, El Alia BP 32, Bab Ezzouar 16111, Algiers (Algeria); Aanesland, A. [Laboratoire de Physique des Plasmas (CNRS, Ecole Polytechnique, Sorbonne Universités, UPMC Univ Paris 06, Univ Paris-Sud), École Polytechnique, 91128 Palaiseau Cedex (France)

    2014-06-15

    Laser photo-detachment is used as a method to measure or determine the negative ion density and temperature in electronegative plasmas. In essence, the method consists of producing an electropositive channel (negative ion free region) via pulsed laser photo-detachment within an electronegative plasma bulk. Electrostatic probes placed in this channel measure the change in the electron density. A second pulse might be used to track the negative ion recovery. From this, the negative ion density and temperature can be determined. We study the formation and relaxation of the electropositive channel via a two-dimensional Particle-In-Cell/Mote Carlo collision model. The simulation is mainly carried out in a Hydrogen plasma with an electronegativity of α = 1, with a parametric study for α up to 20. The temporal and spatial evolution of the plasma potential and the electron densities shows the formation of a double layer (DL) confining the photo-detached electrons within the electropositive channel. This DL evolves into two fronts that move in the opposite directions inside and outside of the laser spot region. As a consequence, within the laser spot region, the background and photo-detached electron energy distribution function relaxes/thermalizes via collisionless effects such as Fermi acceleration and Landau damping. Moreover, the simulations show that collisional effects and the DL electric field strength might play a non-negligible role in the negative ion recovery within the laser spot region, leading to a two-temperature negative ion distribution. The latter result might have important effects in the determination of the negative ion density and temperature from laser photo detachment diagnostic.

  11. Charging of mesospheric aerosol particles: the role of photodetachment and photoionization from meteoric smoke and ice particles

    Directory of Open Access Journals (Sweden)

    M. Rapp

    2009-06-01

    Full Text Available Time constants for photodetachment, photoemission, and electron capture are considered for two classes of mesospheric aerosol particles, i.e., meteor smoke particles (MSPs and pure water ice particles. Assuming that MSPs consist of metal oxides like Fe2O3 or SiO, we find that during daytime conditions photodetachment by solar photons is up to 4 orders of magnitude faster than electron attachment such that MSPs cannot be negatively charged in the presence of sunlight. Rather, even photoemission can compete with electron capture unless the electron density becomes very large (>>1000 cm−3 such that MSPs should either be positively charged or neutral in the case of large electron densities. For pure water ice particles, however, both photodetachment and photoemission are negligible due to the wavelength characteristics of its absorption cross section and because the flux of solar photons has already dropped significantly at such short wavelengths. This means that water ice particles should normally be negatively charged. Hence, our results can readily explain the repeated observation of the coexistence of positive and negative aerosol particles in the polar summer mesopause, i.e., small MSPs should be positively charged and ice particles should be negatively charged. These results have further important implications for our understanding of the nucleation of mesospheric ice particles as well as for the interpretation of incoherent scatter radar observations of MSPs.

  12. Charging of mesospheric aerosol particles: the role of photodetachment and photoionization from meteoric smoke and ice particles

    Directory of Open Access Journals (Sweden)

    M. Rapp

    2009-06-01

    Full Text Available Time constants for photodetachment, photoemission, and electron capture are considered for two classes of mesospheric aerosol particles, i.e., meteor smoke particles (MSPs and pure water ice particles. Assuming that MSPs consist of metal oxides like Fe2O3 or SiO, we find that during daytime conditions photodetachment by solar photons is up to 4 orders of magnitude faster than electron attachment such that MSPs cannot be negatively charged in the presence of sunlight. Rather, even photoemission can compete with electron capture unless the electron density becomes very large (>>1000 cm−3 such that MSPs should either be positively charged or neutral in the case of large electron densities. For pure water ice particles, however, both photodetachment and photoemission are negligible due to the wavelength characteristics of its absorption cross section and because the flux of solar photons has already dropped significantly at such short wavelengths. This means that water ice particles should normally be negatively charged. Hence, our results can readily explain the repeated observation of the coexistence of positive and negative aerosol particles in the polar summer mesopause, i.e., small MSPs should be positively charged and ice particles should be negatively charged. These results have further important implications for our understanding of the nucleation of mesospheric ice particles as well as for the interpretation of incoherent scatter radar observations of MSPs.

  13. Measurements of threshold behavior for one- and two-electron photodetachment from the H/sup -/ ion

    Energy Technology Data Exchange (ETDEWEB)

    Frost, C.A.

    1981-09-01

    One and two-electron photodetachment from the H/sup -/ ion by a single photon has been studied using a crossed beam apparatus. A Q-switched laser beam was directed across the 800 MeV H/sup -/ beam at LAMPF (..beta..=0.842) resulting in Doppler-shifted photon energies in the H/sup -/ barycentric frame, which were tunable from 0.4 eV to 15.5 eV by changing the intersection angle. The particles (e/sup -/, H/sup 0/, H/sup +/) resulting from photodetachment reactions were magnetically deflected into scintillation detectors allowing the total and partial cross sections for 1e/sup -/ and 2e/sup -/ processes to be separately measured. The 2e/sup -/ signal (H/sup +/) was produced by two different mechanisms, the true signal ..gamma.. + H/sup -/ ..-->.. H/sup +/ + 2e/sup -/ and the background process ..gamma.. + H/sup -/ ..-->.. H/sup 0/(n), followed by motional electric field ionization of excited H/sup 0/. Two-electron photodetachment which had been predicted theoretically was observed for the first time, and the relative cross section was measured from threshold to 15.5 eV.

  14. Photodetachment of electron of polyanions: fundamental aspects and application to mass spectrometry

    International Nuclear Information System (INIS)

    Brunet, Claire

    2012-01-01

    This research thesis reports a study of optical properties and of photo-fragmentation of proteins in gas phase. After an overview of the different techniques of fragmentation and optical spectroscopy used for the characterisation of proteins, the author presents the experimental apparatus which implements a coupling of optical spectroscopy (UV/visible laser) and mass spectrometry (LTQ, linear trap quadrupole). Then, she reports the structural characterisation of proteins for a large range of wavelength (from UV to visible), and the study of the properties of the electron emitted by the measurement of its kinetic energy by photo-electron spectroscopy. She shows that the UV-visible radiation can also be used to study optical properties of radical anions by means of an experimental installation with two colours. The last part addresses the technique of dissociation by electron photodetachment which is notably compared with dissociation by electron detachment on a set of peptides of different sizes and negatively charged. The complementarity of these both techniques is discussed [fr

  15. Imaging a multidimensional multichannel potential energy surface: Photodetachment of H(-)(NH3) and NH4 (.).

    Science.gov (United States)

    Hu, Qichi; Song, Hongwei; Johnson, Christopher J; Li, Jun; Guo, Hua; Continetti, Robert E

    2016-06-28

    Probes of the Born-Oppenheimer potential energy surfaces governing polyatomic molecules often rely on spectroscopy for the bound regions or collision experiments in the continuum. A combined spectroscopic and half-collision approach to image nuclear dynamics in a multidimensional and multichannel system is reported here. The Rydberg radical NH4 and the double Rydberg anion NH4 (-) represent a polyatomic system for benchmarking electronic structure and nine-dimensional quantum dynamics calculations. Photodetachment of the H(-)(NH3) ion-dipole complex and the NH4 (-) DRA probes different regions on the neutral NH4 PES. Photoelectron energy and angular distributions at photon energies of 1.17, 1.60, and 2.33 eV compare well with quantum dynamics. Photoelectron-photofragment coincidence experiments indicate dissociation of the nascent NH4 Rydberg radical occurs to H + NH3 with a peak kinetic energy of 0.13 eV, showing the ground state of NH4 to be unstable, decaying by tunneling-induced dissociation on a time scale beyond the present scope of multidimensional quantum dynamics.

  16. Photodetachment and electron reactivity in 1-methyl-1-butyl-pyrrolidinium bis(trifluoromethylsulfonyl)amide

    Energy Technology Data Exchange (ETDEWEB)

    Molins i Domenech, Francesc; FitzPatrick, Benjamin; Healy, Andrew T.; Blank, David A. [Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota 55455 (United States)

    2012-07-21

    The transient absorption spectrum in the range 500 nm-1000 nm was measured with ultrafast time resolution on a flowing neat, aliphatic, room-temperature ionic liquid following anion photodetachment. In this region the spectrum was shown to be a combination of absorption from the electron and the hole. Spectrally-resolved electron quenching determined a bimodal shape for the hole spectrum in agreement with recent computational predictions on a smaller aliphatic ionic liquid [Margulis et al., J. Am. Chem. Soc. 133, 20186 (2011)]. For time delays beyond 15 ps, spectral evolution qualitatively agrees with recent radiolysis experiments [Wishart et al., Faraday Discuss. 154, 353 (2012)]. However, the shape of the spectrum is different, reflecting the contrast in ionization energy between the two methods. Previously unobserved reactivity of the electron was found with a time constant of 300 fs. The results demonstrate solvent control of the rate coefficient for reaction between the electron and proton, with a rapid decline in the rate within the first picosecond.

  17. Electron-atom spin asymmetry and two-electron photodetachment - Addenda to the Coulomb-dipole threshold law

    Science.gov (United States)

    Temkin, A.

    1984-01-01

    Temkin (1982) has derived the ionization threshold law based on a Coulomb-dipole theory of the ionization process. The present investigation is concerned with a reexamination of several aspects of the Coulomb-dipole threshold law. Attention is given to the energy scale of the logarithmic denominator, the spin-asymmetry parameter, and an estimate of alpha and the energy range of validity of the threshold law, taking into account the result of the two-electron photodetachment experiment conducted by Donahue et al. (1984).

  18. Modeling Photodetachment from HO2- Using the pd Case of the Generalized Mixed Character Molecular Orbital Model

    Science.gov (United States)

    Blackstone, Christopher C.; Sanov, Andrei

    2016-06-01

    Using the generalized model for photodetachment of electrons from mixed-character molecular orbitals, we gain insight into the nature of the HOMO of HO2- by treating it as a coherent superpostion of one p- and one d-type atomic orbital. Fitting the pd model function to the ab initio calculated HOMO of HO2- yields a fractional d-character, γp, of 0.979. The modeled curve of the anisotropy parameter, β, as a function of electron kinetic energy for a pd-type mixed character orbital is matched to the experimental data.

  19. What is the difference in the p-wave and s-wave photodetachment in an electric field?

    OpenAIRE

    Du, M. L.

    2009-01-01

    By applying closed-orbit theory to an existing model, a simple formula is derived for the modulation function of s-wave photo-detachment in the presence of a static electric field. We then compare the s-wave modulation function with the p-wave modulation function. We show the maximums (minimums) in the s-wave modulation function correspond to the minimums (maximums) in the p-wave modulation function because of a phase difference of $\\pi$ in their oscillations. The oscillation amplitude in the...

  20. Mediatization

    DEFF Research Database (Denmark)

    Hjarvard, Stig

    2017-01-01

    Mediatization research shares media effects studies' ambition of answering the difficult questions with regard to whether and how media matter and influence contemporary culture and society. The two approaches nevertheless differ fundamentally in that mediatization research seeks answers...... to these general questions by distinguishing between two concepts: mediation and mediatization. The media effects tradition generally considers the effects of the media to be a result of individuals being exposed to media content, i.e. effects are seen as an outcome of mediated communication. Mediatization...... research is concerned with long-term structural changes involving media, culture, and society, i.e. the influences of the media are understood in relation to how media are implicated in social and cultural changes and how these processes come to create new conditions for human communication and interaction...

  1. Vibration mixer

    Energy Technology Data Exchange (ETDEWEB)

    Alekhin, S.A.; Chernov, V.S.; Denisenko, V.V.; Gorodnyanskiy, I.F.; Prokopov, L.I.; Tikhonov, Yu.P.

    1983-01-01

    The vibration mixer is proposed which contains a housing, vibration drive with rod installed in the upper part of the mixing mechanism made in the form of a hollow shaft with blades. In order to improve intensity of mixing and dispersion of the mud, the shaft with the blades is arranged on the rod of the vibrator and is equipped with a cam coupling whose drive disc is attached to the vibration rod. The rod is made helical, while the drive disc of the cam coupling is attached to the helical surface of the rod. In addition, the vibration mixer is equipped with perforated discs installed on the ends of the rods.

  2. Measurement of the electron affinity of As and the fine structure of As- using infrared threshold photodetachment spectroscopy

    International Nuclear Information System (INIS)

    Walter, C W; Gibson, N D; Field, R L III; Snedden, A P; Shapiro, J Z; Janczak, C M; Hanstorp, D

    2009-01-01

    The negative ion As - has been investigated using infrared threshold photodetachment spectroscopy. The relative cross section for neutral atom production was measured with a crossed OPO-ion beam apparatus over selected photon energy ranges between 0.63 - 0.82 eV. s-wave thresholds were observed for detachment from As - (4p 4 3 P 0,1,2 ) to the As (4p 3 4 S 3/2 ) ground state. The measurements yield preliminary values for the electron affinity of As (0.8048(2)) eV) and the fine structure intervals of As - (0.1276(2) eV for 3 P 1 - 3 P 2 and 0.1643(10) eV for 3 P 0 - 3 P 2 ). The present results substantially reduce the uncertainties in these quantities.

  3. Ship Vibrations

    DEFF Research Database (Denmark)

    Sørensen, Herman

    1997-01-01

    Methods for calculating natural frequencies for ship hulls and for plates and panels.Evaluation of the risk for inconvenient vibrations on board......Methods for calculating natural frequencies for ship hulls and for plates and panels.Evaluation of the risk for inconvenient vibrations on board...

  4. Near-threshold infrared photodetachment of Al-: A determination of the electron affinity of aluminum and the range of validity of the Wigner law

    International Nuclear Information System (INIS)

    Calabrese, D.; Covington, A.M.; Thompson, J.S.; Marawar, R.W.; Farley, J.W.

    1996-01-01

    The relative photodetachment cross section of Al - has been measured in the wavelength range 2420 endash 2820 nm (0.440 endash 0.512 eV), using a coaxial ion-laser beams apparatus, in which a 2.98-keV Al - beam is merged with a beam from an F-center laser. The cross-section data near the 3 P 0,1,2 → 2 P 1/2,3/2 photodetachment threshold have been fitted to the Wigner threshold law and to the zero-core-contribution theory of photodetachment. The electron affinity of aluminum was determined to be 0.44094(+0.00066/-0.00048) eV, after correcting the experimental threshold for unresolved fine structure in the ground states of Al - and Al. The new measurement is in agreement with the best previous measurement (0.441±0.010 eV) and is 20 times more precise. The Wigner law agrees with experiment within a few percent for photon energies within 3% of threshold. A proposed leading correction to the Wigner law is discussed. copyright 1996 The American Physical Society

  5. Depletion of the excited state population in negative ions using laser photodetachment in a gas-filled RF quadrupole ion guide

    Energy Technology Data Exchange (ETDEWEB)

    Lindahl, A O; Hanstorp, D [Department of Physics, University of Gothenburg, SE-412 96 Gothenburg (Sweden); Forstner, O [VERA Laboratory, Faculty of Physics, Universitaet Wien, Vienna (Austria); Gibson, N D [Department of Physics and Astronomy, Denison University, Granville, OH 43023 (United States); Gottwald, T; Wendt, K [Institut fuer Physik, Johannes Gutenberg-Universitaet, Mainz, 55099 Mainz (Germany); Havener, C C; Liu, Y, E-mail: Dag.Hanstorp@physics.gu.s [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6368 (United States)

    2010-06-14

    The depopulation of excited states in beams of negatively charged carbon and silicon ions was demonstrated using collisional detachment and laser photodetachment in a radio-frequency quadrupole ion guide filled with helium. The high-lying, loosely bound {sup 2}D excited state in C{sup -} was completely depleted through collisional detachment alone, which was quantitatively determined within 6%. For Si{sup -} the combined signal from the population in the {sup 2}P and {sup 2}D excited states was only partly depleted through collisions in the cooler. The loosely bound {sup 2}P state was likely to be completely depopulated, and the more tightly bound {sup 2}D state was partly depopulated through collisions. 98(2)% of the remaining {sup 2}D population was removed by photodetachment in the cooler using less than 2 W laser power. The total reduction of the excited population in Si{sup -}, including collisional detachment and photodetachment, was estimated to be 99(1)%. Employing this novel technique to produce a pure ground state negative ion beam offers possibilities of enhancing selectivity, as well as accuracy, in high-precision experiments on atomic as well as molecular negative ions.

  6. Urban vibrations

    DEFF Research Database (Denmark)

    Morrison, Ann; Knudsen, L.; Andersen, Hans Jørgen

    2012-01-01

    In   this   paper   we   describe   a   field   study   conducted   with   a   wearable   vibration   belt   where   we   test   to   determine   the   vibration   intensity   sensitivity   ranges   on   a   large   diverse   group   of   participants   with   evenly   distributed  ages  and...

  7. Kinetics of highly vibrationally excited O2(X) molecules in inductively-coupled oxygen plasmas

    Science.gov (United States)

    Annušová, Adriana; Marinov, Daniil; Booth, Jean-Paul; Sirse, Nishant; Lino da Silva, Mário; Lopez, Bruno; Guerra, Vasco

    2018-04-01

    The high degree of vibrational excitation of O2 ground state molecules recently observed in inductively coupled plasma discharges is investigated experimentally in more detail and interpreted using a detailed self-consistent 0D global kinetic model for oxygen plasmas. Additional experimental results are presented and used to validate the model. The vibrational kinetics considers vibrational levels up to v = 41 and accounts for electron impact excitation and de-excitation (e-V), vibration-to-translation relaxation (V-T) in collisions with O2 molecules and O atoms, vibration-to-vibration energy exchanges (V-V), excitation of electronically excited states, dissociative electron attachment, and electron impact dissociation. Measurements were performed at pressures of 10–80 mTorr (1.33 and 10.67 Pa) and radio frequency (13.56 MHz) powers up to 500 W. The simulation results are compared with the absolute densities in each O2 vibrational level obtained by high sensitivity absorption spectroscopy measurements of the Schumann–Runge bands for O2(X, v = 4–18), O(3 P) atom density measurements by two-photon absorption laser induced fluorescence (TALIF) calibrated against Xe, and laser photodetachment measurements of the O‑ negative ions. The highly excited O2(X, v) distribution exhibits a shape similar to a Treanor-Gordiets distribution, but its origin lies in electron impact e-V collisions and not in V-V up-pumping, in contrast to what happens in all other molecular gases known to date. The relaxation of vibrational quanta is mainly due to V-T energy-transfer collisions with O atoms and to electron impact dissociation of vibrationally excited molecules, e+O2(X, v)→O(3P)+O(3P).

  8. Determining partial differential cross sections for low-energy electron photodetachment involving conical intersections using the solution of a Lippmann-Schwinger equation constructed with standard electronic structure techniques.

    Science.gov (United States)

    Han, Seungsuk; Yarkony, David R

    2011-05-07

    A method for obtaining partial differential cross sections for low energy electron photodetachment in which the electronic states of the residual molecule are strongly coupled by conical intersections is reported. The method is based on the iterative solution to a Lippmann-Schwinger equation, using a zeroth order Hamiltonian consisting of the bound nonadiabatically coupled residual molecule and a free electron. The solution to the Lippmann-Schwinger equation involves only standard electronic structure techniques and a standard three-dimensional free particle Green's function quadrature for which fast techniques exist. The transition dipole moment for electron photodetachment, is a sum of matrix elements each involving one nonorthogonal orbital obtained from the solution to the Lippmann-Schwinger equation. An expression for the electron photodetachment transition dipole matrix element in terms of Dyson orbitals, which does not make the usual orthogonality assumptions, is derived.

  9. Vibrating minds

    CERN Multimedia

    2009-01-01

    Ed Witten is one of the leading scientists in the field of string theory, the theory that describes elementary particles as vibrating strings. This week he leaves CERN after having spent a few months here on sabbatical. His wish is that the LHC will unveil supersymmetry.

  10. Vibrational spectroscopy

    Science.gov (United States)

    Umesh P. Agarwal; Rajai Atalla

    2010-01-01

    Vibrational spectroscopy is an important tool in modern chemistry. In the past two decades, thanks to significant improvements in instrumentation and the development of new interpretive tools, it has become increasingly important for studies of lignin. This chapter presents the three important instrumental methods-Raman spectroscopy, infrared (IR) spectroscopy, and...

  11. Discharge source coupled to a deceleration unit for anion beam generation: Application to H{sub 2}{sup −} photodetachment

    Energy Technology Data Exchange (ETDEWEB)

    Rudnev, V.; Ureña, A. González [Unidad de Láseres y Haces Moleculares, Instituto Pluridisciplinar, Universidad Complutense, Juan XXIII-1, Madrid 28040 (Spain)

    2013-12-15

    A cathode discharge source coupled to a deceleration unit for anion beam generation is described. The discharge source, made of stainless steel or duralumin electrodes and Macor insulators, is attached to the exit nozzle valve plate at one end, and to an Einzel lens to the other end. Subsequently, a cylindrical retardation unit is attached to the Einzel lens to decelerate the ions in order to optimize the laser beam interaction time required for spectroscopic investigations. The compact device is able to produce beam intensities of the order of 2 × 10{sup 12} anions/cm{sup 2} s and 20 μrad of angular divergence with kinetic energies ranging from 30 to 120 eV. Using distinct gas mixtures for the supersonic expansion together with a linear time-of-flight spectrometer, anions of great relevance in molecular astrophysics like, for example, H{sub 2}{sup −}, C{sub 3}H{sup −}, C{sub 2}{sup −}, C{sub 2}H{sup −}, HCN{sub 2}{sup −}, CO{sub 2}{sup −}, CO{sub 2}H{sup −}, C{sub 4}{sup −}, C{sub 4}H{sup −}, C{sub 5}H{sub 4}{sup −}, C{sub 5}H{sub 6}{sup −}, C{sub 7}N{sup −}, and C{sub 10}N{sup −} were produced. Finally, in order to demonstrate the capability of the experimental technique the photodetachment cross-section of the metastable H{sub 2}{sup −}, predominantly in the (v = 0, J = 26) state, was measured following laser excitation at λ{sub exc}= 565 nm obtaining a value of σ{sub ph}= 0.04 Å. To the best of our knowledge, it is the first time that this anion cross-section has been measured.

  12. Hot Ground Vibration Tests

    Data.gov (United States)

    National Aeronautics and Space Administration — Ground vibration tests or modal surveys are routinely conducted to support flutter analysis for subsonic and supersonic vehicles. However, vibration testing...

  13. Theory of vibration protection

    CERN Document Server

    Karnovsky, Igor A

    2016-01-01

    This text is an advancement of the theory of vibration protection of mechanical systems with lumped and distributed parameters. The book offers various concepts and methods of solving vibration protection problems, discusses the advantages and disadvantages of different methods, and the fields of their effective applications. Fundamental approaches of vibration protection, which are considered in this book, are the passive, parametric and optimal active vibration protection. The passive vibration protection is based on vibration isolation, vibration damping and dynamic absorbers. Parametric vibration protection theory is based on the Shchipanov-Luzin invariance principle. Optimal active vibration protection theory is based on the Pontryagin principle and the Krein moment method. The book also contains special topics such as suppression of vibrations at the source of their occurrence and the harmful influence of vibrations on humans. Numerous examples, which illustrate the theoretical ideas of each chapter, ar...

  14. Study of Pair and many-body interactions in rare-gas halide atom clusters using negative ion zero electron kinetic energy (ZEKE) and threshold photodetachment spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Yourshaw, Ivan [Univ. of California, Berkeley, CA (United States)

    1998-07-09

    The diatomic halogen atom-rare gas diatomic complexes KrBr-, XeBr-, and KrCl- are studied in this work by zero electron kinetic energy (ZEKE) spectroscopy in order to characterize the weak intermolecular diatomic potentials of these species. Also, the ZEKE and threshold photodetachment spectra of the polyatomic clusters ArnBr- (n = 2-9) and ArnI- (n = 2-19) are studied to obtain information about the non-additive effects on the interactions among the atoms. This work is part of an ongoing effort to characterize the pair and many-body potentials of the complete series of rare gas halide clusters. In these studies we obtain information about both the anionic and neutral clusters.

  15. Resonance hairpin and Langmuir probe-assisted laser photodetachment measurements of the negative ion density in a pulsed dc magnetron discharge

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, James W.; Dodd, Robert; You, S.-D.; Sirse, Nishant; Karkari, Shantanu Kumar [Department of Electrical Engineering and Electronics, University of Liverpool, Liverpool (United Kingdom); National Centre for Plasma Science and Technology, Dublin City University, Dublin 9, Republic of Ireland (Ireland); National Centre for Plasma Science and Technology, Dublin City University, Dublin 9, Republic of Ireland and Institute for Plasma Research, Bhat Gandhinagar, Gujarat (India)

    2011-05-15

    The time-resolved negative oxygen ion density n{sub -} close to the center line in a reactive pulsed dc magnetron discharge (10 kHz and 50% duty cycle) has been determined for the first time using a combination of laser photodetachment and resonance hairpin probing. The discharge was operated at a power of 50 W in 70% argon and 30% oxygen gas mixtures at 1.3 Pa pressure. The results show that the O{sup -} density remains pretty constant during the driven phase of the discharge at values typically below 5x10{sup 14} m{sup -3}; however, in the off-time, the O{sup -} density grows reaching values several times those in the on-time. This leads to the negative ion fraction (or degree of electronegativity) {alpha}=n{sub -}/n{sub e} being higher in the off phase (maximum value {alpha}{approx}1) than in the on phase ({alpha}=0.05-0.3). The authors also see higher values of {alpha} at positions close to the magnetic null than in the more magnetized region of the plasma. This fractional increase in negative ion density during the off-phase is attributed to the enhanced dissociative electron attachment of highly excited oxygen molecules in the cooling plasma. The results show that close to the magnetic null the photodetached electron density decays quickly after the laser pulse, followed by a slow decay over a few microseconds governed by the negative ion temperature. However, in the magnetized regions of the plasma, this decay is more gradual. This is attributed to the different cross-field transport rates for electrons in these two regions. The resonance hairpin probe measurements of the photoelectron densities are compared directly to photoelectron currents obtained using a conventional Langmuir probe. There is good agreement in the general trends, particularly in the off-time.

  16. Vibration of machine

    International Nuclear Information System (INIS)

    Kwak, Mun Gyu; Na, Sung Su; Baek, Gwang Hyeon; Song, Chul Gi; Han, Sang Bo

    2001-09-01

    This book deals with vibration of machine which gives descriptions of free vibration using SDOF system, forced vibration using SDOF system, vibration of multi-degree of freedom system like introduction and normal form, distribution system such as introduction, free vibration of bar and practice problem, approximate solution like lumped approximations and Raleigh's quotient, engineering by intuition and experience, real problem and experimental method such as technology of signal, fourier transform analysis, frequency analysis and sensor and actuator.

  17. Enhanced vibration diagnostics using vibration signature analysis

    International Nuclear Information System (INIS)

    Ahmed, S.; Shehzad, K.; Zahoor, Y.; Mahmood, A.; Bibi, A.

    2001-01-01

    Symptoms will appear in equipment, as well as in human beings. when 'suffering from sickness. Symptoms of abnormality in equipment are vibration, noise, deformation, temperature, pressure, electric current, crack, wearing, leakage etc. these are called modes of failure. If the mode of failure is vibration then the vibration signature analysis can be effectively used in order to diagnose the machinery problems. Much valuable information is contained within these vibration 'Spectra' or 'Signatures' but is only of use if the analyst can unlock its 'Secrets'. This paper documents a vibration problem in the motor of a centrifugal pump (Type ETA). It focuses mainly on the roll of modern vibration monitoring system in problem analysis. The problem experienced was the motor unstability and noise due to high vibration. Using enhanced vibration signature data, the problem was analyzed. which suggested that the rotor eccentricity was the cause of excessive noise and vibration in the motor. In conclusion, advanced electronic monitoring and diagnostic systems provide powerful information for machine's condition assessment and problem analysis. Appropriate interpretation and use of this information is important for accurate and effective vibration analysis. (author)

  18. Probing the pre-reactive a Cl (2P) + H2(D2) Van der Waals well through the photodetachment spectroscopy of Cl- H2(D2). CP-31

    International Nuclear Information System (INIS)

    Ghosal, Subhas; Mahapatra, Susanta

    2004-01-01

    The photodetachment spectrum of ClH 2 - and ClD 2 , probing the van der Waals well region of the reactive Cl( 2 P) + H 2 (D 2 ) potential energy surface, is theoretically calculated and compared with the experiment. A time-dependent wave packet approach is employed using the Capecchi-Werner coupled multi-sheeted ab initio potential energy surfaces of neutral ClH 2 for this purpose

  19. [Occupational standing vibration rate and vibrational diseases].

    Science.gov (United States)

    Karnaukh, N G; Vyshchipan, V F; Haumenko, B S

    2003-12-01

    Occupational standing vibration rate is proposed in evaluating a degree of impairment of an organism activity. It will allow more widely to introduce specification of quality and quantity in assessment of the development of vibrational disease. According out-patient and inpatient obtained data we have established criterial values of functional changes in accordance with accumulated occupational standing vibration rate. The nomogram was worked out for defining a risk of the development of vibrational disease in mine workers. This nomogram more objectively can help in diagnostics of the disease.

  20. Portable vibration exciter

    Science.gov (United States)

    Beecher, L. C.; Williams, F. T.

    1970-01-01

    Gas-driven vibration exciter produces a sinusoidal excitation function controllable in frequency and in amplitude. It allows direct vibration testing of components under normal loads, removing the possibility of component damage due to high static pressure.

  1. Vibrations and Eigenvalues

    Indian Academy of Sciences (India)

    We make music by causing strings, membranes, or air columns to vibrate. Engineers design safe structures by control- ling vibrations. I will describe to you a very simple vibrating system and the mathematics needed to analyse it. The ideas were born in the work of Joseph-Louis Lagrange (1736–1813), and I begin by quot-.

  2. Vibration of hydraulic machinery

    CERN Document Server

    Wu, Yulin; Liu, Shuhong; Dou, Hua-Shu; Qian, Zhongdong

    2013-01-01

    Vibration of Hydraulic Machinery deals with the vibration problem which has significant influence on the safety and reliable operation of hydraulic machinery. It provides new achievements and the latest developments in these areas, even in the basic areas of this subject. The present book covers the fundamentals of mechanical vibration and rotordynamics as well as their main numerical models and analysis methods for the vibration prediction. The mechanical and hydraulic excitations to the vibration are analyzed, and the pressure fluctuations induced by the unsteady turbulent flow is predicted in order to obtain the unsteady loads. This book also discusses the loads, constraint conditions and the elastic and damping characters of the mechanical system, the structure dynamic analysis, the rotor dynamic analysis and the system instability of hydraulic machines, including the illustration of monitoring system for the instability and the vibration in hydraulic units. All the problems are necessary for vibration pr...

  3. Anti-vibration gloves?

    Science.gov (United States)

    Hewitt, Sue; Dong, Ren G; Welcome, Daniel E; McDowell, Thomas W

    2015-03-01

    For exposure to hand-transmitted vibration (HTV), personal protective equipment is sold in the form of anti-vibration (AV) gloves, but it remains unclear how much these gloves actually reduce vibration exposure or prevent the development of hand-arm vibration syndrome in the workplace. This commentary describes some of the issues that surround the classification of AV gloves, the assessment of their effectiveness and their applicability in the workplace. The available information shows that AV gloves are unreliable as devices for controlling HTV exposures. Other means of vibration control, such as using alternative production techniques, low-vibration machinery, routine preventative maintenance regimes, and controlling exposure durations are far more likely to deliver effective vibration reductions and should be implemented. Furthermore, AV gloves may introduce some adverse effects such as increasing grip force and reducing manual dexterity. Therefore, one should balance the benefits of AV gloves and their potential adverse effects if their use is considered. © Crown copyright 2014.

  4. Imaging a multidimensional multichannel potential energy surface: Photodetachment of H{sup −}(NH{sub 3}) and NH{sub 4}{sup −}

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Qichi; Johnson, Christopher J.; Continetti, Robert E., E-mail: hguo@umn.edu, E-mail: rcontinetti@ucsd.edu [Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0340 (United States); Song, Hongwei; Guo, Hua, E-mail: hguo@umn.edu, E-mail: rcontinetti@ucsd.edu [Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131 (United States); Li, Jun [School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044 (China)

    2016-06-28

    Probes of the Born-Oppenheimer potential energy surfaces governing polyatomic molecules often rely on spectroscopy for the bound regions or collision experiments in the continuum. A combined spectroscopic and half-collision approach to image nuclear dynamics in a multidimensional and multichannel system is reported here. The Rydberg radical NH{sub 4} and the double Rydberg anion NH{sub 4}{sup −} represent a polyatomic system for benchmarking electronic structure and nine-dimensional quantum dynamics calculations. Photodetachment of the H{sup −}(NH{sub 3}) ion-dipole complex and the NH{sub 4}{sup −} DRA probes different regions on the neutral NH{sub 4} PES. Photoelectron energy and angular distributions at photon energies of 1.17, 1.60, and 2.33 eV compare well with quantum dynamics. Photoelectron-photofragment coincidence experiments indicate dissociation of the nascent NH{sub 4} Rydberg radical occurs to H + NH{sub 3} with a peak kinetic energy of 0.13 eV, showing the ground state of NH{sub 4} to be unstable, decaying by tunneling-induced dissociation on a time scale beyond the present scope of multidimensional quantum dynamics.

  5. Bandshapes in vibrational spectroscopy

    International Nuclear Information System (INIS)

    Dijkman, F.G.

    1978-01-01

    A detailed account is given of the development of modern bandshape theories since 1965. An investigation into the relative contributions of statistical irreversible relaxation processes is described, for a series of molecules in which gradually the length of one molecular axis is increased. An investigation into the theoretical and experimental investigation of the broadening brought about by the effect of fluctuating intermolecular potentials on the vibrational frequency is also described. The effect of an intermolecular perturbative potential on anharmonic and Morse oscillators is discussed and the results are presented of a computation on the broadening of the vibrational band of some diatomic molecules in a rigid lattice type solvent. The broadening of the OH-stretching vibration in a number of aliphatic alcohols, the vibrational bandshapes of the acetylenic C-H stretching vibration and of the symmetric methyl stretching vibration are investigated. (Auth./ C.F.)

  6. Transfer vibration through spine

    OpenAIRE

    Benyovszky, Adam

    2012-01-01

    Transfer Vibration through Spine Abstract In the bachelor project we deal with the topic of Transfer Vibration through Spine. The problem of TVS is trying to be solved by the critical review method. We analyse some diagnostic methods and methods of treatment based on this principle. Close attention is paid to the method of Transfer Vibration through Spine that is being currently solved by The Research Institute of Thermomechanics in The Czech Academy of Sciences in cooperation with Faculty of...

  7. Mechanical vibration and shock analysis, sinusoidal vibration

    CERN Document Server

    Lalanne, Christian

    2014-01-01

    Everything engineers need to know about mechanical vibration and shock...in one authoritative reference work! This fully updated and revised 3rd edition addresses the entire field of mechanical vibration and shock as one of the most important types of load and stress applied to structures, machines and components in the real world. Examples include everything from the regular and predictable loads applied to turbines, motors or helicopters by the spinning of their constituent parts to the ability of buildings to withstand damage from wind loads or explosions, and the need for cars to m

  8. Hydroelastic Vibrations of Ships

    DEFF Research Database (Denmark)

    Jensen, Jørgen Juncher; Folsø, Rasmus

    2002-01-01

    A formula for the necessary hull girder bending stiffness required to avoid serious springing vibrations is derived. The expression takes into account the zero crossing period of the waves, the ship speed and main dimensions. For whipping vibrations the probability of exceedance for the combined...

  9. Surface vibrational spectroscopy

    International Nuclear Information System (INIS)

    Erskine, J.L.

    1984-01-01

    A brief review of recent studies which combine measurements of surface vibrational energies with lattice dynamical calculations is presented. These results suggest that surface vibrational spectroscopy offers interesting prospects for use as a molecular-level probe of surface geometry, adsorbate bond distances and molecular orientations

  10. Gearbox vibration diagnostic analyzer

    Science.gov (United States)

    1992-01-01

    This report describes the Gearbox Vibration Diagnostic Analyzer installed in the NASA Lewis Research Center's 500 HP Helicopter Transmission Test Stand to monitor gearbox testing. The vibration of the gearbox is analyzed using diagnostic algorithms to calculate a parameter indicating damaged components.

  11. Handbook Of Noise And Vibration

    International Nuclear Information System (INIS)

    1995-12-01

    This book is about noise and vibration. The first chapter has explanations of noise such as basic of sound, influence of noise, assessment of noise, measurement of prevention of noise and technology, case of noise measurement and soundproof. The second chapter describes vibration with outline, theory of vibration, interpretation of vibration, measurement for reduction of vibration, case of design of protection against vibration. It deals with related regulation and method of measurement.

  12. Vibration insensitive interferometry

    Science.gov (United States)

    Millerd, James; Brock, Neal; Hayes, John; Kimbrough, Brad; North-Morris, Michael; Wyant, James C.

    2017-11-01

    The largest limitation of phase-shifting interferometry for optical testing is the sensitivity to the environment, both vibration and air turbulence. An interferometer using temporal phase-shifting is very sensitive to vibration because the various phase shifted frames of interferometric data are taken at different times and vibration causes the phase shifts between the data frames to be different from what is desired. Vibration effects can be reduced by taking all the phase shifted frames simultaneously and turbulence effects can be reduced by averaging many measurements. There are several techniques for simultaneously obtaining several phase-shifted interferograms and this paper will discuss two such techniques: 1) Simultaneous phase-shifting interferometry on a single detector array (PhaseCam) and 2) Micropolarizer phase-shifting array. The application of these techniques for the testing of large optical components, measurement of vibrational modes, the phasing of segmented optical components, and the measurement of deformations of large diffuse structures is described.

  13. Vibrations of rotating machinery

    CERN Document Server

    Matsushita, Osami; Kanki, Hiroshi; Kobayashi, Masao; Keogh, Patrick

    2017-01-01

    This book opens with an explanation of the vibrations of a single degree-of-freedom (dof) system for all beginners. Subsequently, vibration analysis of multi-dof systems is explained by modal analysis. Mode synthesis modeling is then introduced for system reduction, which aids understanding in a simplified manner of how complicated rotors behave. Rotor balancing techniques are offered for rigid and flexible rotors through several examples. Consideration of gyroscopic influences on the rotordynamics is then provided and vibration evaluation of a rotor-bearing system is emphasized in terms of forward and backward whirl rotor motions through eigenvalue (natural frequency and damping ratio) analysis. In addition to these rotordynamics concerning rotating shaft vibration measured in a stationary reference frame, blade vibrations are analyzed with Coriolis forces expressed in a rotating reference frame. Other phenomena that may be assessed in stationary and rotating reference frames include stability characteristic...

  14. Photodetachment of free hexahalogenometallate doubly charged anions in the gas phase: [ML6]2-, (M=Re, Os, Ir, Pt; L=Cl and Br)

    International Nuclear Information System (INIS)

    Wang, X.; Wang, L.

    1999-01-01

    We report the first observation and photodetachment photoelectron spectroscopic study of a series of hexahalogenometallates dianions MCl 6 2- (M=Re, Os, Ir, and Pt) and MBr 6 2- (M=Re, Ir, and Pt) in the gas phase. All of these species were found to be stable as free gaseous doubly charged anions. Photoelectron spectra of all the dianions were obtained at several detachment photon energies. The photon-energy-dependent spectra clearly revealed the dianion nature of these species and allowed the repulsive Coulomb barriers to be estimated. The binding energies of the second excess electron in MCl 6 2- (M=Re, Os, Ir, Pt) were determined to be 0.46 (5), 0.46 (5), 0.82 (5), and 1.58 (5) eV, respectively, and those in MBr 6 2- (M=Re, Ir, Pt) to be 0.76 (6), 0.96 (6), and 1.52 (6) eV, respectively. A wealth of electronic structure information about these metal complexes were obtained and low-lying and highly-excited electronic states of the corresponding singly charged anions were observed. Detachment from metal d orbitals or ligand orbitals were observed and could be clearly distinguished; detachments from the metal d-orbitals all occur at low binding energies whereas those from the ligand-dominated orbitals all take place at rather high binding energies. We also found a remarkable correlation between electron affinities measured in vacuo and the redox potentials obtained in the solution phase of these species. copyright 1999 American Institute of Physics

  15. Vibrational energy relaxation: proposed pathway of fast local chromatin denaturation

    International Nuclear Information System (INIS)

    Harder, D.; Greinert, R.

    2002-01-01

    The molecular mechanism responsible for the a component of exchange-type chromosome aberrations, of chromosome fragmentation and of reproductive cell death is one of the unsolved issues of radiation biology. Under review is whether vibrational energy relaxation in the constitutive biopolymers of chromatin, induced by inelastic energy deposition events and mediated via highly excited vibrational states, may provide a pathway of fast local chromatin denaturation, thereby producing the severe DNA lesion able to interact chemically with other, non-damaged chromatin. (author)

  16. Partial cross sections for Rb- photodetachment in the region of the Rb(5p2Psub(1/2,3/2)) thresholds and their analysis by multichannel quantum defect theory

    International Nuclear Information System (INIS)

    Frey, P.; Lawen, M.; Breyer, F.; Klar, H.; Hotop, H.

    1982-01-01

    A crossed ion-laser beam apparatus has been used to measure accurate relative total and partial cross sections for photodetachment from Rb - ions with high photon energy resolution (0.1-0.6 cm -1 ) in the region of the Rb(5p 2 Psub(1/2,3/2)) thresholds (photon energy range 16.350-16.820 cm -1 ). Satisfactory fits to these data by multichannel quantum defect theory (MQDT) have been obtained, resulting in a reliable set of seven MQDT parameters. The electron angular distribution parameter for the Rb(5s) channel was found to be β(5s)=2, independent of photon energy, MQDT predicts a sharp, window-type variation of β(5s) around the minimum of the 5s-cross section below the Rb(5p 2 Psub(1/2)) threshold (where an accurate experimental measurement of β(5s) was not possible) and a similar behaviour of β(6s) in the case of Cs - photodetachment below the Cs(6p 2 Psub(1/2)) threshold. (orig.)

  17. Silicon micromachined vibrating gyroscopes

    Science.gov (United States)

    Voss, Ralf

    1997-09-01

    This work gives an overview of silicon micromachined vibrating gyroscopes. Market perspectives and fields of application are pointed out. The advantage of using silicon micromachining is discussed and estimations of the desired performance, especially for automobiles are given. The general principle of vibrating gyroscopes is explained. Vibrating silicon gyroscopes can be divided into seven classes. for each class the characteristic principle is presented and examples are given. Finally a specific sensor, based on a tuning fork for automotive applications with a sensitivity of 250(mu) V/degrees is described in detail.

  18. System Detects Vibrational Instabilities

    Science.gov (United States)

    Bozeman, Richard J., Jr.

    1990-01-01

    Sustained vibrations at two critical frequencies trigger diagnostic response or shutdown. Vibration-analyzing electronic system detects instabilities of combustion in rocket engine. Controls pulse-mode firing of engine and identifies vibrations above threshold amplitude at 5.9 and/or 12kHz. Adapted to other detection and/or control schemes involving simultaneous real-time detection of signals above or below preset amplitudes at two or more specified frequencies. Potential applications include rotating machinery and encoders and decoders in security systems.

  19. Coherent vibrational dynamics

    CERN Document Server

    Lanzani, Guglielmo; De Silvestri, Sandro

    2007-01-01

    Vibrational spectroscopy is a powerful investigation tool for a wide class of materials covering diverse areas in physics, chemistry and biology. The continuous development in the laser field regarding ultrashort pulse generation has led to the possibility of producing light pulses that can follow vibrational motion coupled to the electronic transitions in molecules and solids in real time. Aimed at researchers and graduate students using vibrational spectroscopy, this book provides both introductory chapters as well as more advanced contents reporting on recent progress. It also provides a good starting point for scientists seeking a sound introduction to ultrafast optics and spectroscopic techniques.

  20. PREFACE: Vibrations at surfaces Vibrations at surfaces

    Science.gov (United States)

    Rahman, Talat S.

    2011-12-01

    This special issue is dedicated to the phenomenon of vibrations at surfaces—a topic that was indispensible a couple of decades ago, since it was one of the few phenomena capable of revealing the nature of binding at solid surfaces. For clean surfaces, the frequencies of modes with characteristic displacement patterns revealed how surface geometry, as well as the nature of binding between atoms in the surface layers, could be different from that in the bulk solid. Dispersion of the surface phonons provided further measures of interatomic interactions. For chemisorbed molecules on surfaces, frequencies and dispersion of the vibrational modes were also critical for determining adsorption sites. In other words, vibrations at surfaces served as a reliable means of extracting information about surface structure, chemisorption and overlayer formation. Experimental techniques, such as electron energy loss spectroscopy and helium-atom-surface scattering, coupled with infra-red spectroscopy, were continually refined and their resolutions enhanced to capture subtleties in the dynamics of atoms and molecules at surfaces. Theoretical methods, whether based on empirical and semi-empirical interatomic potential or on ab initio electronic structure calculations, helped decipher experimental observations and provide deeper insights into the nature of the bond between atoms and molecules in regions of reduced symmetry, as encountered on solid surfaces. Vibrations at surfaces were thus an integral part of the set of phenomena that characterized surface science. Dedicated workshops and conferences were held to explore the variety of interesting and puzzling features revealed in experimental and theoretical investigations of surface vibrational modes and their dispersion. One such conference, Vibrations at Surfaces, first organized by Harald Ibach in Juelich in 1980, continues to this day. The 13th International Conference on Vibrations at Surfaces was held at the University of

  1. Vibration Theory, Vol. 3

    DEFF Research Database (Denmark)

    Nielsen, Søren R. K.

    The present textbook has been written based on previous lecture notes for a course on stochastic vibration theory that is being given on the 9th semester at Aalborg University for M. Sc. students in structural engineering. The present 4th edition of this textbook on linear stochastic vibration th...... theory is unchanged in comparison to the 3rd edition. Only a few errors have been corrected.......The present textbook has been written based on previous lecture notes for a course on stochastic vibration theory that is being given on the 9th semester at Aalborg University for M. Sc. students in structural engineering. The present 4th edition of this textbook on linear stochastic vibration...

  2. Improved Laser Vibration Radar

    National Research Council Canada - National Science Library

    Hilaire, Pierre

    1998-01-01

    .... This thesis reconfigured an existing CO2 laboratory laser radar system that is capable of measuring the frequencies of vibration of a simulated target into a more compact and rugged form for field testing...

  3. NIF Ambient Vibration Measurements

    International Nuclear Information System (INIS)

    Noble, C.R.; Hoehler, M.S.; S.C. Sommer

    1999-01-01

    LLNL has an ongoing research and development project that includes developing data acquisition systems with remote wireless communication for monitoring the vibrations of large civil engineering structures. In order to establish the capability of performing remote sensing over an extended period of time, the researchers needed to apply this technology to a real structure. The construction of the National Ignition Facility provided an opportunity to test the data acquisition system on a large structure to monitor whether the facility is remaining within the strict ambient vibration guidelines. This document will briefly discuss the NIF ambient vibration requirements and summarize the vibration measurements performed during the Spring and Summer of 1999. In addition, a brief description of the sensors and the data acquisition systems will be provided in Appendix B

  4. A vibration sieve

    Energy Technology Data Exchange (ETDEWEB)

    Alekhin, S.A.; Denisenko, V.V.; Dzhalalov, M.G.; Kirichek, F.P.; Pitatel, Yu.A.; Prokopov, L.I.; Tikhonov, Yu.P.

    1982-01-01

    A vibration sieve is proposed which includes a vibration drive, a body and a screen installed on shock absorbers, a device for washing out the screen, and a subassembly for loading the material. To increase the operational reliability and effectiveness of the vibration sieve by improving the cleaning of the screen, the loading subassembly is equipped with a baffle with a lever which is hinged to it. The device for washing out the screen is made in the form of an electromagnet with a connecting rod, a switch and an eccentric, a friction ratchet mechanism and sprinkling systems. Here, the latter are interconnected, using a connecting rod, while the sprinkling system is installed on rollers under the screen. The electromagnetic switch is installed under the lever. The body is made with grooves for installing the sprinkling system. The vibration sieve is equipped with a switch which interacts with the connecting rod. The friction ratchet mechanism is equipped with a lug.

  5. Structural Stability and Vibration

    DEFF Research Database (Denmark)

    Wiggers, Sine Leergaard; Pedersen, Pauli

    This book offers an integrated introduction to the topic of stability and vibration. Strikingly, it describes stability as a function of boundary conditions and eigenfrequency as a function of both boundary conditions and column force. Based on a post graduate course held by the author at the Uni...... and their derivation, thus stimulating them to write interactive and dynamic programs to analyze instability and vibrational modes....

  6. 2008 Vibrational Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Philip J. Reid

    2009-09-21

    The conference focuses on using vibrational spectroscopy to probe structure and dynamics of molecules in gases, liquids, and interfaces. The goal is to bring together a collection of researchers who share common interests and who will gain from discussing work at the forefront of several connected areas. The intent is to emphasize the insights and understanding that studies of vibrations provide about a variety of systems.

  7. Vibration transducer calibration techniques

    Science.gov (United States)

    Brinkley, D. J.

    1980-09-01

    Techniques for the calibration of vibration transducers used in the Aeronautical Quality Assurance Directorate of the British Ministry of Defence are presented. Following a review of the types of measurements necessary in the calibration of vibration transducers, the performance requirements of vibration transducers, which can be used to measure acceleration, velocity or vibration amplitude, are discussed, with particular attention given to the piezoelectric accelerometer. Techniques for the accurate measurement of sinusoidal vibration amplitude in reference-grade transducers are then considered, including the use of a position sensitive photocell and the use of a Michelson laser interferometer. Means of comparing the output of working-grade accelerometers with that of previously calibrated reference-grade devices are then outlined, with attention given to a method employing a capacitance bridge technique and a method to be used at temperatures between -50 and 200 C. Automatic calibration procedures developed to speed up the calibration process are outlined, and future possible extensions of system software are indicated.

  8. Recovering Intrinsic Fragmental Vibrations Using the Generalized Subsystem Vibrational Analysis.

    Science.gov (United States)

    Tao, Yunwen; Tian, Chuan; Verma, Niraj; Zou, Wenli; Wang, Chao; Cremer, Dieter; Kraka, Elfi

    2018-05-08

    Normal vibrational modes are generally delocalized over the molecular system, which makes it difficult to assign certain vibrations to specific fragments or functional groups. We introduce a new approach, the Generalized Subsystem Vibrational Analysis (GSVA), to extract the intrinsic fragmental vibrations of any fragment/subsystem from the whole system via the evaluation of the corresponding effective Hessian matrix. The retention of the curvature information with regard to the potential energy surface for the effective Hessian matrix endows our approach with a concrete physical basis and enables the normal vibrational modes of different molecular systems to be legitimately comparable. Furthermore, the intrinsic fragmental vibrations act as a new link between the Konkoli-Cremer local vibrational modes and the normal vibrational modes.

  9. Vibrations in orthopedics.

    Science.gov (United States)

    Nokes, L D; Thorne, G C

    1988-01-01

    Measurements of various mechanical properties of skeletal material using vibration techniques have been reported. The purposes of such investigations include the monitoring of pathogenic disorders such as osteoporosis, the rate and extent of fracture healing, and the status of internal fixations. Early investigations pioneered the application of conventional vibration measurement equipment to biological systems. The more recent advent of the microcomputer has made available to research groups more sophisticated techniques for data acquisition and analysis. The economical advantages of such equipment has led to the development of portable research instrumentation which lends itself to use in a clinical environment. This review article reports on the developments and progression of the various vibrational techniques and theories as applied to musculoskeletal systems.

  10. Vibrational spectra of aminoacetonitrile

    International Nuclear Information System (INIS)

    Bak, B.; Hansen, E.L.; Nicolaisen, F.M.; Nielsen, O.F.

    1975-01-01

    The preparation of pure, stable aminoacetonitrile(1-amino, 1'-cyanomethane)CH 2 NH 2 CN (1) is described. The Raman spectrum, now complete, and a novel infrared spectrum extending over the 50-3600 cm -1 region are reported. A tentative normal vibration analysis is presented and supported by Raman and infrared data from the spectra of CH 2 NHDCN (2) and CH 2 ND 2 CN (3). The predominance of the trans rotamer may be attributed to intramolecular hydrogen bonding but this is too unimportant to influence the vibrational frequencies of gaseous 1, 2, and 3. However, large gas/liquid frequency shifts occur. (author)

  11. Vibrations and waves

    CERN Document Server

    Kaliski, S

    2013-01-01

    This book gives a comprehensive overview of wave phenomena in different media with interacting mechanical, electromagnetic and other fields. Equations describing wave propagation in linear and non-linear elastic media are followed by equations of rheological models, models with internal rotational degrees of freedom and non-local interactions. Equations for coupled fields: thermal, elastic, electromagnetic, piezoelectric, and magneto-spin with adequate boundary conditions are also included. Together with its companion volume Vibrations and Waves. Part A: Vibrations this work provides a wealth

  12. Vibration Theory, Vol. 3

    DEFF Research Database (Denmark)

    Nielsen, Søren R. K.

    The present textbook has been written based on previous lecture notes for a course on stochastic vibration theory that is being given on the 9th semester at Aalborg University for M. Sc. students in structural engineering. The present 2nd edition of this textbook on linear stochastic vibration th...... theory is basically unchanged in comparison to the 1st edition. Only section 4.2 on single input - single output systems and chapter 6 on offshore structures have been modified in order to enhance the clearness....

  13. Heterogeneous Dynamics of Coupled Vibrations

    NARCIS (Netherlands)

    Cringus, Dan; Jansen, Thomas I. C.; Pshenichnikov, Maxim S.; Schoenlein, RW; Corkum, P; DeSilvestri, S; Nelson, KA; Riedle, E

    2009-01-01

    Frequency-dependent dynamics of coupled stretch vibrations of a water molecule are revealed by 2D IR correlation spectroscopy. These are caused by non-Gaussian fluctuations of the environment around the individual OH stretch vibrations.

  14. Vibration in car repair work.

    Science.gov (United States)

    Hansson, J E; Eklund, L; Kihlberg, S; Ostergren, C E

    1987-03-01

    The main objective of the study was to find efficient hand tools which caused only minor vibration loading. Vibration measurements were carried out under standardised working conditions. The time during which car body repairers in seven companies were exposed to vibration was determined. Chisel hammers, impact wrenches, sanders and saws were the types of tools which generated the highest vibration accelerations. The average daily exposure at the different garages ranged from 22 to 70 min. The risk of vibration injury is currently rated as high. The difference between the highest and lowest levels of vibration was considerable in most tool categories. Therefore the choice of tool has a major impact on the magnitude of vibration exposure. The importance of choosing the right tools and working methods is discussed and a counselling service on vibration is proposed.

  15. Structural Stability and Vibration

    DEFF Research Database (Denmark)

    Wiggers, Sine Leergaard; Pedersen, Pauli

    at the University of Southern Denmark, it reports on fundamental formulas and makes uses of graphical representation to promote understanding. Thanks to the emphasis put on analytical methods and numerical results, the book is meant to make students and engineers familiar with all fundamental equations...... and their derivation, thus stimulating them to write interactive and dynamic programs to analyze instability and vibrational modes....

  16. Vibrational Spectroscopy and Astrobiology

    Science.gov (United States)

    Chaban, Galina M.; Kwak, D. (Technical Monitor)

    2001-01-01

    Role of vibrational spectroscopy in solving problems related to astrobiology will be discussed. Vibrational (infrared) spectroscopy is a very sensitive tool for identifying molecules. Theoretical approach used in this work is based on direct computation of anharmonic vibrational frequencies and intensities from electronic structure codes. One of the applications of this computational technique is possible identification of biological building blocks (amino acids, small peptides, DNA bases) in the interstellar medium (ISM). Identifying small biological molecules in the ISM is very important from the point of view of origin of life. Hybrid (quantum mechanics/molecular mechanics) theoretical techniques will be discussed that may allow to obtain accurate vibrational spectra of biomolecular building blocks and to create a database of spectroscopic signatures that can assist observations of these molecules in space. Another application of the direct computational spectroscopy technique is to help to design and analyze experimental observations of ice surfaces of one of the Jupiter's moons, Europa, that possibly contains hydrated salts. The presence of hydrated salts on the surface can be an indication of a subsurface ocean and the possible existence of life forms inhabiting such an ocean.

  17. Vibrations and Eigenvalues

    Indian Academy of Sciences (India)

    The vibrating string problem is the source of much mathe- matics and physics. ... ing this science [mechanics],and the art of solving the problems pertaining to it, to .... used tools for finding maxima and minima of functions of several variables.

  18. Heat exchanger vibration

    International Nuclear Information System (INIS)

    Richards, D.J.W.

    1977-01-01

    The heat exchangers of various types are common items of plant in the generation and transmission of electricity. The amount of attention given to the flow-induced vibrations of heat exchangers by designers is usually related to the operational history of similar items of plant. Consequently, if a particular design procedure yields items of plant which behave in a satisfactory manner during their operational life, there is little incentive to improve or refine the design procedure. On the other hand, failures of heat exchangers clearly indicate deficiencies in the design procedures or in the data available to the designer. When such failures are attributable to flow-induced vibrations, the identification of the mechanisms involved is a prime importance. Ideally, basic research work provides the background understanding and the techniques necessary to be able to identify the important mechanisms. In practice, the investigation of a flow-induced vibration problem may identify the presence of mechanisms but may not be able to quantify their effects adequately. In these circumstances the need for additional work is established and the objectives of the research programme emerge. The purpose of this paper is to outline the background to the current research programme at C.E.R.L. on heat exchanger vibration

  19. Man-Induced Vibrations

    DEFF Research Database (Denmark)

    Jönsson, Jeppe; Hansen, Lars Pilegaard

    1994-01-01

    work has been done on the measurement of the exact load functions and related reponse analysis. A recent work using a spectral description has been performed by Per-Erik Erikson and includes a good literature survey. Bachmann and Ammann give a good overview of vibrations caused by human activity. Other...

  20. Heat exchanger vibration

    Energy Technology Data Exchange (ETDEWEB)

    Richards, D J.W. [CERL, CEGB, Leatherhead, Surrey (United Kingdom)

    1977-12-01

    The heat exchangers of various types are common items of plant in the generation and transmission of electricity. The amount of attention given to the flow-induced vibrations of heat exchangers by designers is usually related to the operational history of similar items of plant. Consequently, if a particular design procedure yields items of plant which behave in a satisfactory manner during their operational life, there is little incentive to improve or refine the design procedure. On the other hand, failures of heat exchangers clearly indicate deficiencies in the design procedures or in the data available to the designer. When such failures are attributable to flow-induced vibrations, the identification of the mechanisms involved is a prime importance. Ideally, basic research work provides the background understanding and the techniques necessary to be able to identify the important mechanisms. In practice, the investigation of a flow-induced vibration problem may identify the presence of mechanisms but may not be able to quantify their effects adequately. In these circumstances the need for additional work is established and the objectives of the research programme emerge. The purpose of this paper is to outline the background to the current research programme at C.E.R.L. on heat exchanger vibration.

  1. General principles of vibrational spectroscopies

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Schoonheydt, R.A.

    2000-01-01

    Atoms in molecules and solids do not remain in fixed relative positions, but vibrate about some mean position. This vibrational motion is quantized and at room temperature, most of the molecules in a given sample are in their lowest vibrational state. Absorption of electromagnetic radiation with

  2. High-Temperature Vibration Damper

    Science.gov (United States)

    Clarke, Alan; Litwin, Joel; Krauss, Harold

    1987-01-01

    Device for damping vibrations functions at temperatures up to 400 degrees F. Dampens vibrational torque loads as high as 1,000 lb-in. but compact enough to be part of helicopter rotor hub. Rotary damper absorbs energy from vibrating rod, dissipating it in turbulent motion of viscous hydraulic fluid forced by moving vanes through small orifices.

  3. The effects of vibration-reducing gloves on finger vibration

    Science.gov (United States)

    Welcome, Daniel E.; Dong, Ren G.; Xu, Xueyan S.; Warren, Christopher; McDowell, Thomas W.

    2015-01-01

    Vibration-reducing (VR) gloves have been used to reduce the hand-transmitted vibration exposures from machines and powered hand tools but their effectiveness remains unclear, especially for finger protection. The objectives of this study are to determine whether VR gloves can attenuate the vibration transmitted to the fingers and to enhance the understanding of the mechanisms of how these gloves work. Seven adult male subjects participated in the experiment. The fixed factors evaluated include hand force (four levels), glove condition (gel-filled, air bladder, no gloves), and location of the finger vibration measurement. A 3-D laser vibrometer was used to measure the vibrations on the fingers with and without wearing a glove on a 3-D hand-arm vibration test system. This study finds that the effect of VR gloves on the finger vibration depends on not only the gloves but also their influence on the distribution of the finger contact stiffness and the grip effort. As a result, the gloves increase the vibration in the fingertip area but marginally reduce the vibration in the proximal area at some frequencies below 100 Hz. On average, the gloves reduce the vibration of the entire fingers by less than 3% at frequencies below 80 Hz but increase at frequencies from 80 to 400 Hz. At higher frequencies, the gel-filled glove is more effective at reducing the finger vibration than the air bladder-filled glove. The implications of these findings are discussed. Relevance to industry Prolonged, intensive exposure to hand-transmitted vibration can cause hand-arm vibration syndrome. Vibration-reducing gloves have been used as an alternative approach to reduce the vibration exposure. However, their effectiveness for reducing finger-transmitted vibrations remains unclear. This study enhanced the understanding of the glove effects on finger vibration and provided useful information on the effectiveness of typical VR gloves at reducing the vibration transmitted to the fingers. The new

  4. Infrared Spectra of the 10-μm Bands of 1,2-Difluoroethane and 1,1,2-Trifluoroethane: Vibrationally Mediated Torsional Tunneling in 1,1,2-Trifluoroethane

    Science.gov (United States)

    Stone, Stephen C.; Miller, C. Cameron; Philips, Laura A.; Andrews, A. M.; Fraser, G. T.; Pate, B. H.; Xu, Li-Hong

    1995-12-01

    The 3-MHz-resolution infrared spectra of the 10-μm bands of thegaucheconformer of 1,2-difluoroethane (HFC152) and theC1-symmetry conformer of 1,1,2-trifluoroethane (HFC143) have been measured using a molecular-beam electric-resonance optothermal spectrometer with a tunable microwave-sideband CO2laser source. For 1,2-difluoroethane, two bands have been studied, the ν17B-symmetry C-F stretch at 1077.3 cm-1and the ν13B-symmetry CH2rock at 896.6 cm-1. Both bands are well fit to a asymmetric-rotor Hamiltonian to better than 0.5 MHz. The ν13band is effectively unperturbed, while the ν17band is weakly perturbed, as shown by the large change in centrifugal distortion constants from the ground state values. Two bands have also been studied for 1,1,2-trifluoroethane, the ν11symmetric CF2stretch at 1077.2 cm-1and the ν13C-C stretch at 905.1 cm-1. One of the two bands, ν11, is unperturbed and fit to near the experimental precision. The ν13vibration, on the other hand, is weakly perturbed by an interaction with a nearby state. This perturbation leads to a doubling or splitting of the lines, due to a perturbation-induced lifting of the degeneracy of the symmetric and antisymmetric tunneling states associated with tunneling between the two equivalentC1forms. For theJ,Kastates studied, the splittings are as large as 37 MHz. Combining this observation with published low-resolution far-infrared measurements of torsional sequence-band and hot-band frequencies and calculations from an empirical torsional potential allows us to identify the perturbing state as ν17+ 6ν18. Here, ν17is the CF2twist and ν18is the torsion. The matrix element responsible for this interaction exchanges eight vibrational quanta!

  5. Vibration of fuel bundles

    International Nuclear Information System (INIS)

    Chen, S.S.

    1975-06-01

    Several mathematical models have been proposed for calculating fuel rod responses in axial flows based on a single rod consideration. The spacing between fuel rods in liquid metal fast breeder reactors is small; hence fuel rods will interact with one another due to fluid coupling. The objective of this paper is to study the coupled vibration of fuel bundles. To account for the fluid coupling, a computer code, AMASS, is developed to calculate added mass coefficients for a group of circular cylinders based on the potential flow theory. The equations of motion for rod bundles are then derived including hydrodynamic forces, drag forces, fluid pressure, gravity effect, axial tension, and damping. Based on the equations, a method of analysis is presented to study the free and forced vibrations of rod bundles. Finally, the method is applied to a typical LMFBR fuel bundle consisting of seven rods

  6. Pickin’ up good vibrations

    CERN Multimedia

    Katarina Anthony

    2015-01-01

    In preparation for the civil engineering work on the HL-LHC, vibration measurements were carried out at the LHC’s Point 1 last month. These measurements will help evaluate how civil engineering work could impact the beam, and will provide crucial details about the site’s geological make-up before construction begins.   A seismic truck at Point 1 generated wave-like vibrations measured by EN/MME. From carrying out R&D to produce state-of-the-art magnets to developing innovative, robust materials capable of withstanding beam impact, the HL-LHC is a multi-faceted project involving many groups and teams across CERN’s departments. It was in this framework that the project management mandated CERN's Mechanical and Materials Engineering (EN/MME) group to measure the propagation of vibrations around Point 1. Their question: can civil engineering work for the HL-LHC – the bulk of which is scheduled for LS2 – begin while the LHC is running? Alth...

  7. Vibrational stability of graphene

    Directory of Open Access Journals (Sweden)

    Yangfan Hu

    2013-05-01

    Full Text Available The mechanical stability of graphene as temperature rises is analyzed based on three different self-consistent phonon (SCP models. Compared with three-dimensional (3-D materials, the critical temperature Ti at which instability occurs for graphene is much closer to its melting temperature Tm obtained from Monte Carlo simulation (Ti ≃ 2Tm, K. V. Zakharchenko, A. Fasolino, J. H. Los, and M. I. Katsnelson, J. Phys. Condens. Matter 23, 202202. This suggests that thermal vibration plays a significant role in melting of graphene while melting for 3-D materials is often dominated by topologic defects. This peculiar property of graphene derives from its high structural anisotropy, which is characterized by the vibrational anisotropic coefficient (VAC, defined upon its Lindermann ratios in different directions. For any carbon based material with a graphene-like structure, the VAC value must be smaller than 5.4 to maintain its stability. It is also found that the high VAC value of graphene is responsible for its negative thermal expansion coefficient at low temperature range. We believe that the VAC can be regarded as a new criterion concerning the vibrational stability of any low-dimensional (low-D materials.

  8. A general analytical expression for the three-dimensional Franck-Condon integral and simulation of the photodetachment spectrum of the PO2- anion

    Science.gov (United States)

    Liang, Jun; Cui, Fang; Wang, Ru; Huang, Wei; Cui, Zhifeng

    2013-04-01

    Calculations of Franck-Condon factors are crucial for interpreting vibronic spectra of molecules and studying nonradiative processes. We have derived straightforwardly a more general analytical expression for the calculation of the three-dimensional Franck-Condon overlap integrals on the basis of harmonic oscillator approximation under the influence of mode mixing effects. This new analytical expression was applied to study the photoelectron spectra of PO2-. The theoretical spectrum obtained by employing CCSD(T) values is in excellent agreement with the observed one. An 'irregular spacing' observed in the experimental photoelectron spectrum of PO2- is interpreted as contributing from a hot-band sequence of the bending vibration ω2 and combination bands of the stretching vibration ω1 and the bending vibration ω2. In addition, the equilibrium geometry parameters, r(O-P) = 1.495 ± 0.005 Å and ∠(O-P-O) = 119.5 ± 0.5°, of theXA1 state of PO2-, are derived by employing an iterative Franck-Condon analysis procedure in the spectral simulation.

  9. Random vibrations theory and practice

    CERN Document Server

    Wirsching, Paul H; Ortiz, Keith

    1995-01-01

    Random Vibrations: Theory and Practice covers the theory and analysis of mechanical and structural systems undergoing random oscillations due to any number of phenomena— from engine noise, turbulent flow, and acoustic noise to wind, ocean waves, earthquakes, and rough pavement. For systems operating in such environments, a random vibration analysis is essential to the safety and reliability of the system. By far the most comprehensive text available on random vibrations, Random Vibrations: Theory and Practice is designed for readers who are new to the subject as well as those who are familiar with the fundamentals and wish to study a particular topic or use the text as an authoritative reference. It is divided into three major sections: fundamental background, random vibration development and applications to design, and random signal analysis. Introductory chapters cover topics in probability, statistics, and random processes that prepare the reader for the development of the theory of random vibrations a...

  10. VIBRATION ISOLATION SYSTEM PROBABILITY ANALYSIS

    Directory of Open Access Journals (Sweden)

    Smirnov Vladimir Alexandrovich

    2012-10-01

    Full Text Available The article deals with the probability analysis for a vibration isolation system of high-precision equipment, which is extremely sensitive to low-frequency oscillations even of submicron amplitude. The external sources of low-frequency vibrations may include the natural city background or internal low-frequency sources inside buildings (pedestrian activity, HVAC. Taking Gauss distribution into account, the author estimates the probability of the relative displacement of the isolated mass being still lower than the vibration criteria. This problem is being solved in the three dimensional space, evolved by the system parameters, including damping and natural frequency. According to this probability distribution, the chance of exceeding the vibration criteria for a vibration isolation system is evaluated. Optimal system parameters - damping and natural frequency - are being developed, thus the possibility of exceeding vibration criteria VC-E and VC-D is assumed to be less than 0.04.

  11. Vibration damping method and apparatus

    Science.gov (United States)

    Redmond, James M.; Barney, Patrick S.; Parker, Gordon G.; Smith, David A.

    1999-01-01

    The present invention provides vibration damping method and apparatus that can damp vibration in more than one direction without requiring disassembly, that can accommodate varying tool dimensions without requiring re-tuning, and that does not interfere with tool tip operations and cooling. The present invention provides active dampening by generating bending moments internal to a structure such as a boring bar to dampen vibration thereof.

  12. Atomic beams probe surface vibrations

    International Nuclear Information System (INIS)

    Robinson, A.L.

    1982-01-01

    In the last two years, surface scientist have begun trying to obtain the vibrational frequencies of surface atoms in both insulating and metallic crystals from beams of helium atoms. It is the inelastic scattering that researchers use to probe surface vibrations. Inelastic atomic beam scattering has only been used to obtain vibrational frequency spectra from clean surfaces. Several experiments using helium beams are cited. (SC)

  13. Digital analysis of vibrations

    International Nuclear Information System (INIS)

    Bohnstedt, H.J.; Walter, G.

    1982-01-01

    Vibrational measurements, e.g. on turbomachinery, can be evaluated rapidly and economically with the aid of a combination of the following instruments: a desk-top computer, a two-channel vector filter and a FFT spectral analyzer. This equipment combination is available within the Allianz Centre for Technology and has also been used for mobile, on-site investigations during the last year. It enables calculation and display of time functions, kinetic shaft orbits, displacement diagrams. Bode plots, polar-coordinate plots, cascade diagrams and histograms. (orig.) [de

  14. Turbine blade vibration dampening

    Science.gov (United States)

    Cornelius, C.C.; Pytanowski, G.P.; Vendituoli, J.S.

    1997-07-08

    The present turbine wheel assembly increases component life and turbine engine longevity. The combination of the strap and the opening combined with the preestablished area of the outer surface of the opening and the preestablished area of the outer circumferential surface of the strap and the friction between the strap and the opening increases the life and longevity of the turbine wheel assembly. Furthermore, the mass ``M`` or combined mass ``CM`` of the strap or straps and the centrifugal force assist in controlling vibrations and damping characteristics. 5 figs.

  15. Lattice Vibrations in Chlorobenzenes:

    DEFF Research Database (Denmark)

    Reynolds, P. A.; Kjems, Jørgen; White, J. W.

    1974-01-01

    Lattice vibrational dispersion curves for the ``intermolecular'' modes in the triclinic, one molecule per unit cell β phase of p‐C6D4Cl2 and p‐C6H4Cl2 have been obtained by inelastic neutron scattering. The deuterated sample was investigated at 295 and at 90°K and a linear extrapolation to 0°K...... was applied in order to correct for anharmonic effects. Calculations based on the atom‐atom model for van der Waals' interaction and on general potential parameters for the aromatic compounds agree reasonably well with the experimental observations. There is no substantial improvement in fit obtained either...

  16. Vibration control, machine diagnostics

    International Nuclear Information System (INIS)

    1990-01-01

    Changing vibrations announce damage in the form of wear or cracks on components of, e.g., engine rotors, pumps, power plant turbo sets, rounding-up tools, or marine diesel engines. Therefore, machine diagnostics use frequency analyses, system tests, trend analyses as well as expert systems to localize or estimate the causes of these damages and malfunctions. Data acquisistion, including not only sensors, but also reliable and redundant data processing systems and analyzing systems, play an important role. The lectures pertaining to the data base are covered in detail. (DG) [de

  17. Off-axis Modal Active Vibration Control Of Rotational Vibrations

    NARCIS (Netherlands)

    Babakhani, B.; de Vries, Theodorus J.A.; van Amerongen, J.

    Collocated active vibration control is an effective and robustly stable way of adding damping to the performance limiting vibrations of a plant. Besides the physical parameters of the Active Damping Unit (ADU) containing the collocated actuator and sensor, its location with respect to the

  18. Vibrational spectra of ordered perovskites

    NARCIS (Netherlands)

    Corsmit, A.F.; Hoefdraad, H.E.; Blasse, G.

    1972-01-01

    The vibrational spectra of the molecular M6+O6 (M = Mo, Te, W) group in ordered perovskites of the type Ba2M2+M6+O6 are reported. These groups have symmetry Oh, whereas their site symmetry is also Oh. An assignment of the internal vibrations is presented.

  19. Vibrations and Stability: Solved Problems

    DEFF Research Database (Denmark)

    Thomsen, Jon Juel

    Worked out solutions for exercise problems in J. J. Thomsen 'Vibrations and Stability: Advanced Theory, Analysis, and Tools', Springer, Berlin - Heidelberg, 2003.......Worked out solutions for exercise problems in J. J. Thomsen 'Vibrations and Stability: Advanced Theory, Analysis, and Tools', Springer, Berlin - Heidelberg, 2003....

  20. Low Cost Digital Vibration Meter.

    Science.gov (United States)

    Payne, W Vance; Geist, Jon

    2007-01-01

    This report describes the development of a low cost, digital Micro Electro Mechanical System (MEMS) vibration meter that reports an approximation to the RMS acceleration of the vibration to which the vibration meter is subjected. The major mechanical element of this vibration meter is a cantilever beam, which is on the order of 500 µm in length, with a piezoresistor deposited at its base. Vibration of the device in the plane perpendicular to the cantilever beam causes it to bend, which produces a measurable change in the resistance of a piezoresistor. These changes in resistance along with a unique signal-processing scheme are used to determine an approximation to the RMS acceleration sensed by the device.

  1. Force illusions and drifts observed during muscle vibration.

    Science.gov (United States)

    Reschechtko, Sasha; Cuadra, Cristian; Latash, Mark L

    2018-01-01

    We explored predictions of a scheme that views position and force perception as a result of measuring proprioceptive signals within a reference frame set by ongoing efferent process. In particular, this hypothesis predicts force illusions caused by muscle vibration and mediated via changes in both afferent and efferent components of kinesthesia. Healthy subjects performed accurate steady force production tasks by pressing with the four fingers of one hand (the task hand) on individual force sensors with and without visual feedback. At various times during the trials, subjects matched the perceived force using the other hand. High-frequency vibration was applied to one or both of the forearms (over the hand and finger extensors). Without visual feedback, subjects showed a drop in the task hand force, which was significantly smaller under the vibration of that forearm. Force production by the matching hand was consistently higher than that of the task hand. Vibrating one of the forearms affected the matching hand in a manner consistent with the perception of higher magnitude of force produced by the vibrated hand. The findings were consistent between the dominant and nondominant hands. The effects of vibration on both force drift and force mismatching suggest that vibration led to shifts in both signals from proprioceptors and the efferent component of perception, the referent coordinate and/or coactivation command. The observations fit the hypothesis on combined perception of kinematic-kinetic variables with little specificity of different groups of peripheral receptors that all contribute to perception of forces and coordinates. NEW & NOTEWORTHY We show that vibration of hand/finger extensors produces consistent errors in finger force perception. Without visual feedback, finger force drifted to lower values without a drift in the matching force produced by the other hand; hand extensor vibration led to smaller finger force drift. The findings fit the scheme with

  2. Lattice vibration spectra. 16

    International Nuclear Information System (INIS)

    Lutz, H.D.; Willich, P.

    1977-01-01

    The FIR absorption spectra of pyrite type compounds RuS 2 , RuSsub(2-x)Sesub(x), RuSe 2 , RuTe 2 , OsS 2 , OsSe 2 , and PtP 2 as well as loellingite type phosphides FeP 2 , RuP 2 , and OsP 2 are reported. For RuS 2 , RuSe 2 , RuTe 2 , OsS 2 , and PtP 2 all of the five infrared allowed modes (k = 0) are observed. As a first result of a numerical normal coordinate treatment vibration forms of pyrite structure are communicated. The spectra show that lattice forces of corresponding sulfides, tellurides, and phosphides are about the same strength, but increase strongly by substitution of iron by ruthenium and especially of ruthenium by osmium. The lattice constants of the RuSsub(2-x)Sesub(x) solid solution obey Vegard's rule. (author)

  3. Vibrational Spectroscopy of Ionic Liquids.

    Science.gov (United States)

    Paschoal, Vitor H; Faria, Luiz F O; Ribeiro, Mauro C C

    2017-05-24

    Vibrational spectroscopy has continued use as a powerful tool to characterize ionic liquids since the literature on room temperature molten salts experienced the rapid increase in number of publications in the 1990's. In the past years, infrared (IR) and Raman spectroscopies have provided insights on ionic interactions and the resulting liquid structure in ionic liquids. A large body of information is now available concerning vibrational spectra of ionic liquids made of many different combinations of anions and cations, but reviews on this literature are scarce. This review is an attempt at filling this gap. Some basic care needed while recording IR or Raman spectra of ionic liquids is explained. We have reviewed the conceptual basis of theoretical frameworks which have been used to interpret vibrational spectra of ionic liquids, helping the reader to distinguish the scope of application of different methods of calculation. Vibrational frequencies observed in IR and Raman spectra of ionic liquids based on different anions and cations are discussed and eventual disagreements between different sources are critically reviewed. The aim is that the reader can use this information while assigning vibrational spectra of an ionic liquid containing another particular combination of anions and cations. Different applications of IR and Raman spectroscopies are given for both pure ionic liquids and solutions. Further issues addressed in this review are the intermolecular vibrations that are more directly probed by the low-frequency range of IR and Raman spectra and the applications of vibrational spectroscopy in studying phase transitions of ionic liquids.

  4. Intercultural Mediation

    OpenAIRE

    Dragos Marian Radulescu; Denisa Mitrut

    2012-01-01

    The Intercultural Mediator facilitates exchanges between people of different socio-cultural backgrounds and acts as a bridge between immigrants and national and local associations, health organizations, services and offices in order to foster integration of every single individual. As the use mediation increases, mediators are more likely to be involved in cross-cultural mediation, but only the best mediators have the opportunity to mediate cross border business disputes or international poli...

  5. Molecular vibrations the theory of infrared and Raman vibrational spectra

    CERN Document Server

    Wilson, E Bright; Cross, Paul C

    1980-01-01

    Pedagogical classic and essential reference focuses on mathematics of detailed vibrational analyses of polyatomic molecules, advancing from application of wave mechanics to potential functions and methods of solving secular determinant.

  6. Putting a damper on drilling's bad vibrations

    Energy Technology Data Exchange (ETDEWEB)

    Jardine, S [Sedco forex, Montrouge (France); Malone, D [Anadrill, Sugar Land, TX (United States); Sheppard, M [Schlumberger Cambridge Research, Cambridge (United Kingdom)

    1994-01-01

    Harmful drilling vibrations are costing the industry dearly. Three main vibration types (axial, torsional and transverse) are explained and its causes discussed. Technology exists to eliminate most vibrations, but requires more systematic deployment than is usual. Hardware that eliminates vibrations is reviewed, including downhole shock measurement, torque feedback shock guards and antiwhirl bits. 9 figs., 11 refs.

  7. [Farmacological effect of retabolil on aldosterone level and arterial pressure in rats under the action of vibrations].

    Science.gov (United States)

    Obut, T A; Ovsiukova, M V; Egorova, S A; Érdynieva, T A; Dement'eva, T Iu; Obut, E T

    2014-01-01

    The experiments were performed on male rats, which were subjected to single and multiply repeated vibrations (low-frequency, horizontal, high-amplitude) analogous to the action of motor transport vibrations. It is established that the administration of retabolil produces a hypotensive effect and blocks the vibration-induced increase in the level of hypertensive hormone aldosterone. Under conditions of the multiply repeated action of vibrations, both effects were realized via micro-opioid receptors. In the case of a single action, these receptors were only involved in a hypotensive effect but not mediated in aldosterone suppression. Both these effects were absent in the control group of animals (not subjected to vibrations). Therefore, retabolil can be used as a hypotensive and aldosterone-blocking drug for vibration-induced hypertension in animals and, probably, in humans.

  8. Vibration measurements of automobile catalyst

    Science.gov (United States)

    Aatola, Seppo

    1994-09-01

    Vibration of catalyst cell, which is inside the casing of the catalyst, is difficult to measure with usual measuring instrumentation. When catalyst is in use, there is hot exhaust gas flow though the catalyst cell and temperature of the cell is approximately +900 degree(s)C. Therefore non-contact Laser- Doppler-Vibrometer was used to measure vibration velocity of the catalyst cell. The laser beam was directed towards the cell through pipe which was put through and welded to the casing of the catalyst. The outer end of the pipe was screw down with a tempered class to prevent exhaust gas flow from the pipe. The inner end of the pipe was open and few millimeters away from the measuring point. Catalyst was attached to the engine with two ways, rigidly close to the engine and flexible under the engine. The engine was running in test bench under controlled conditions. Vibration measurements were carried out during constant running speeds of the engine. Vibration signals were captured and analyzed with FFT-analyzer. Vibration of catalyst cell was strongest at running speed of 5000 rpm, from 10 to 20 g (1 g equals 9.81 ms-2), when catalyst was attached rigidly close to the engine. At running speed of 3000 rpm, vibration of catalyst cell was from 2 to 3 g in most cases, when catalyst was attached either rigidly or flexible to the engine. It is estimated that in real life, i.e. when catalyst is attached to car with same engine, vibration of catalyst cell at running speed of 5000 rpm is somewhere between 1 and 10 g. At running speed of 3000 rpm, which may be more often used when driving car (car speed approximately 100 kmh-1), vibration of catalyst cell is probably few g's.

  9. Smart accelerometer. [vibration damage detection

    Science.gov (United States)

    Bozeman, Richard J., Jr. (Inventor)

    1994-01-01

    The invention discloses methods and apparatus for detecting vibrations from machines which indicate an impending malfunction for the purpose of preventing additional damage and allowing for an orderly shutdown or a change in mode of operation. The method and apparatus is especially suited for reliable operation in providing thruster control data concerning unstable vibration in an electrical environment which is typically noisy and in which unrecognized ground loops may exist.

  10. Vibrational excitation from heterogeneous catalysis

    International Nuclear Information System (INIS)

    Purvis, G.D. III; Redmon, M.J.; Woken, G. Jr.

    1979-01-01

    Classical trajectories have been used by numerous researchers to investigate the dynamics of exothermic chemical reactions (atom + diatom) with a view toward understanding what leads to vibrational excitation of the product molecule. Unlike these studies, the case where the reaction is catalyzed by a solid surface is considered. The trajectory studies indicate that there should be conditions under which considerable vibrational energy appears in the product molecules without being lost to the solid during the course of the reaction. 2 figures, 3 tables

  11. Vibrational Spectral Studies of Gemfibrozil

    Science.gov (United States)

    Benitta, T. Asenath; Balendiran, G. K.; James, C.

    2008-11-01

    The Fourier Transform Raman and infrared spectra of the crystallized drug molecule 5-(2,5-Dimethylphenoxy)-2,2-dimethylpentanoic acid (Gemfibrozil) have been recorded and analyzed. Quantum chemical computational methods have been employed using Gaussian 03 software package based on Hartree Fock method for theoretically modeling the grown molecule. The optimized geometry and vibrational frequencies have been predicted. Observed vibrational modes have been assigned with the aid of normal coordinate analysis.

  12. Neuropathic pain-like alterations in muscle nociceptor function associated with vibration-induced muscle pain.

    Science.gov (United States)

    Chen, Xiaojie; Green, Paul G; Levine, Jon D

    2010-11-01

    We recently developed a rodent model of the painful muscle disorders induced by occupational exposure to vibration. In the present study we used this model to evaluate the function of sensory neurons innervating the vibration-exposed gastrocnemius muscle. Activity of 74 vibration-exposed and 40 control nociceptors, with mechanical receptive fields in the gastrocnemius muscle, were recorded. In vibration-exposed rats ∼15% of nociceptors demonstrated an intense and long-lasting barrage of action potentials in response to sustained suprathreshold mechanical stimulation (average of 2635 action potentials with frequency of ∼44Hz during a 1min suprathreshold stimulus) much greater than that has been reported to be produced even by potent inflammatory mediators. While these high-firing nociceptors had lower mechanical thresholds than the remaining nociceptors, exposure to vibration had no effect on conduction velocity and did not induce spontaneous activity. Hyperactivity was not observed in any of 19 neurons from vibration-exposed rats pretreated with intrathecal antisense for the IL-6 receptor subunit gp130. Since vibration can injure peripheral nerves and IL-6 has been implicated in painful peripheral neuropathies, we suggest that the dramatic change in sensory neuron function and development of muscles pain, induced by exposure to vibration, reflects a neuropathic muscle pain syndrome. Copyright © 2010 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

  13. Vibrational spectroscopy of proteins

    International Nuclear Information System (INIS)

    Schwaighofer, A.

    2013-01-01

    Two important steps for the development of a biosensor are the immobilization of the biological component (e.g. protein) on a surface and the enhancement of the signal to improve the sensitivity of detection. To address these subjects, the present work describes Fourier transform infrared (FTIR) investigations of several proteins bound to the surface of an attenuated total reflection (ATR) crystal. Furthermore, new nanostructured surfaces for signal enhancement were developed for use in FTIR microscopy. The mitochondrial redox-protein cytochrome c oxidase (CcO) was incorporated into a protein-tethered bilayer lipid membrane (ptBLM) on an ATR crystal featuring a roughened two-layer gold surface for signal enhancement. Electrochemical excitation by periodic potential pulses at different modulation frequencies was followed by time-resolved FTIR spectroscopy. Phase sensitive detection was used for deconvolution of the IR spectra into vibrational components. A model based on protonation-dependent chemical reaction kinetics could be fitted to the time evolution of IR bands attributed to several different redox centers of the CcO. Further investigations involved the odorant binding protein 14 (OBP14) of the honey bee (Apis mellifera), which was studied using ATR-FTIR spectroscopy and circular dichroism. OBP14 was found to be thermally stable up to 45 °C, thus permitting the potential application of this protein for the fabrication of biosensors. Thermal denaturation measurements showed that odorant binding increases the thermal stability of the OBP-odorant complex. In another project, plasmonic nanostructures were fabricated that enhance the absorbance in FTIR microscopy measurements. The nanostructures are composed of an array of round-shaped insulator and gold discs on top of a continuous gold layer. Enhancement factors of up to ⁓125 could be observed with self-assembled monolayers of dodecanethiol molecules immobilized on the gold surface (author) [de

  14. Adaptive learning algorithms for vibration energy harvesting

    International Nuclear Information System (INIS)

    Ward, John K; Behrens, Sam

    2008-01-01

    By scavenging energy from their local environment, portable electronic devices such as MEMS devices, mobile phones, radios and wireless sensors can achieve greater run times with potentially lower weight. Vibration energy harvesting is one such approach where energy from parasitic vibrations can be converted into electrical energy through the use of piezoelectric and electromagnetic transducers. Parasitic vibrations come from a range of sources such as human movement, wind, seismic forces and traffic. Existing approaches to vibration energy harvesting typically utilize a rectifier circuit, which is tuned to the resonant frequency of the harvesting structure and the dominant frequency of vibration. We have developed a novel approach to vibration energy harvesting, including adaptation to non-periodic vibrations so as to extract the maximum amount of vibration energy available. Experimental results of an experimental apparatus using an off-the-shelf transducer (i.e. speaker coil) show mechanical vibration to electrical energy conversion efficiencies of 27–34%

  15. Mediation Analysis with Multiple Mediators.

    Science.gov (United States)

    VanderWeele, T J; Vansteelandt, S

    2014-01-01

    Recent advances in the causal inference literature on mediation have extended traditional approaches to direct and indirect effects to settings that allow for interactions and non-linearities. In this paper, these approaches from causal inference are further extended to settings in which multiple mediators may be of interest. Two analytic approaches, one based on regression and one based on weighting are proposed to estimate the effect mediated through multiple mediators and the effects through other pathways. The approaches proposed here accommodate exposure-mediator interactions and, to a certain extent, mediator-mediator interactions as well. The methods handle binary or continuous mediators and binary, continuous or count outcomes. When the mediators affect one another, the strategy of trying to assess direct and indirect effects one mediator at a time will in general fail; the approach given in this paper can still be used. A characterization is moreover given as to when the sum of the mediated effects for multiple mediators considered separately will be equal to the mediated effect of all of the mediators considered jointly. The approach proposed in this paper is robust to unmeasured common causes of two or more mediators.

  16. PC based vibration monitoring system

    International Nuclear Information System (INIS)

    Jain, Sanjay K.; Roy, D.A.; Pithawa, C.K.; Patil, R.K.

    2004-01-01

    Health of large rotating machinery gets reflected in the vibration signature of the rotor and supporting structures and proper recording of these signals and their analysis can give a clear picture of the health of the machine. Using these data and their trending, it is possible to predict an impending trouble in the machine so that preventive action can be taken in time and catastrophic failure can be avoided. Continuous monitoring and analysis can give quick warning and enable operator to take preventive measures. Reactor Control Division, BARC is developing a PC based Vibration monitoring system for turbo generator machinery. The System can acquire 20 vibration signals at a rate of 5000 samples per second and also 15 process signals at a rate of 100 samples/ sec. The software for vibration monitoring system includes acquisition modules, analysis modules and Graphical User Interface module. The acquisition module involves initialization, setting of required parameters and acquiring the data from PC-based data acquisition cards. The acquired raw vibration data is then stored for analysis using various software packages. The display and analysis of acquired data is done in LabVIEW 7.0 where the data is displayed in time as well as frequency domain along with the RMS value of the signal. (author)

  17. On generalized fractional vibration equation

    International Nuclear Information System (INIS)

    Dai, Hongzhe; Zheng, Zhibao; Wang, Wei

    2017-01-01

    Highlights: • The paper presents a generalized fractional vibration equation for arbitrary viscoelastically damped system. • Some classical vibration equations can be derived from the developed equation. • The analytic solution of developed equation is derived under some special cases. • The generalized equation is particularly useful for developing new fractional equivalent linearization method. - Abstract: In this paper, a generalized fractional vibration equation with multi-terms of fractional dissipation is developed to describe the dynamical response of an arbitrary viscoelastically damped system. It is shown that many classical equations of motion, e.g., the Bagley–Torvik equation, can be derived from the developed equation. The Laplace transform is utilized to solve the generalized equation and the analytic solution under some special cases is derived. Example demonstrates the generalized transfer function of an arbitrary viscoelastic system.

  18. General vibration monitoring: Experimental hall

    International Nuclear Information System (INIS)

    Jendrzejczyk, J.A.; Wambsganss, M.W.; Smith, R.K.

    1993-01-01

    The reported vibration data were generated from measurements made on the experimental hall floor on December 2, 1992. At the time of the measurements, the ESRF hydrolevel was set-up in the Early Assembly Area (EAA) of the experimental hall and was being used to measure static displacement (settlement) of the floor. The vibration measurement area was on and adjacent to the EAA, in the vicinity of the ESRF hydrolevel test which was in progress. This report summarizes the objectives, instrumentation, measurement locations, observations, and conclusions, and provides selected results in the form of RMS vs. time plots, and power spectral densities from which frequency information can be derived. Measured response amplitudes were within the vibration criteria established for the APS

  19. Fundamental Vibration of Molecular Hydrogen

    Science.gov (United States)

    Dickenson, G. D.; Niu, M. L.; Salumbides, E. J.; Komasa, J.; Eikema, K. S. E.; Pachucki, K.; Ubachs, W.

    2013-05-01

    The fundamental ground tone vibration of H2, HD, and D2 is determined to an accuracy of 2×10-4cm-1 from Doppler-free laser spectroscopy in the collisionless environment of a molecular beam. This rotationless vibrational splitting is derived from the combination difference between electronic excitation from the X1Σg+, v=0, and v=1 levels to a common EF1Σg+, v=0 level. Agreement within 1σ between the experimental result and a full ab initio calculation provides a stringent test of quantum electrodynamics in a chemically bound system.

  20. The Shock and Vibration Bulletin. Part 2. Vibration Analysis.

    Science.gov (United States)

    1977-09-01

    J.N. Tait, Naval Air Development Center, Warminster, PA EVALUATION OF AN ADAPTIVE FILTER AS A DIGITAL TRACKING FILTER D.O. Smallwood and D.L. Gregory...Oklahoma Norman , Oklahoma In contrast to the considerable information abailable on free vibration of isotropic plates, there is only a very limited

  1. Shock and Vibration. Volume 1, Issue 1

    National Research Council Canada - National Science Library

    Pilkey, Walter D

    1994-01-01

    ..., and earthquake engineering. Among the specific areas to be covered are vibration testing and control, vibration condition monitoring and diagnostics, shock hardenings, modal technology, shock testing, data acquisition, fluid...

  2. Novel active vibration absorber with magnetorheological fluid

    Energy Technology Data Exchange (ETDEWEB)

    Gerlach, T; Ehrlich, J; Boese, H [Fraunhofer-Institut fuer Silicatforschung ISC, Neunerplatz 2, D-97082 Wuerzburg (Germany)], E-mail: thomas.gerlach@isc.fraunhofer.de

    2009-02-01

    Disturbing vibrations diminish the performance of technical high precision devices significantly. In search of a suitable solution for reducing these vibrations, a novel concept of active vibration reduction was developed which exploits the special properties of magnetorheological fluids. In order to evaluate the concept of such an active vibration absorber (AVA) a demonstrator was designed and manufactured. This demonstrator generates a force which counteracts the motion of the vibrating body. Since the counterforce is generated by a centrifugal exciter, the AVA provides the capability to compensate vibrations even in two dimensions. To control the strength of the force transmitted to the vibrating body, the exciter is based on a tunable MR coupling. The AVA was integrated in an appropriate testing device to investigate its performance. The recorded results show a significant reduction of the vibration amplitudes by an order of magnitude.

  3. Isotope separation using vibrationally excited molecules

    International Nuclear Information System (INIS)

    1979-01-01

    This invention relates to isotope separation employing isotopically selective vibrational excitation and vibration-translation reactions of the excited particles. Uranium enrichment, using uranium hexafluoride, is a particular embodiment. (U.K.)

  4. Predicting Statistical Distributions of Footbridge Vibrations

    DEFF Research Database (Denmark)

    Pedersen, Lars; Frier, Christian

    2009-01-01

    The paper considers vibration response of footbridges to pedestrian loading. Employing Newmark and Monte Carlo simulation methods, a statistical distribution of bridge vibration levels is calculated modelling walking parameters such as step frequency and stride length as random variables...

  5. Application of eigenfunction orthogonalities to vibration problems

    CSIR Research Space (South Africa)

    Fedotov, I

    2009-07-01

    Full Text Available The modelling of vibration problems is of great importance in engineering. A popular method of analysing such problems is the variational method. The simplest vibration model is represented using the example of a long rod. Two kinds...

  6. Mediation Analysis with Multiple Mediators

    OpenAIRE

    VanderWeele, T.J.; Vansteelandt, S.

    2014-01-01

    Recent advances in the causal inference literature on mediation have extended traditional approaches to direct and indirect effects to settings that allow for interactions and non-linearities. In this paper, these approaches from causal inference are further extended to settings in which multiple mediators may be of interest. Two analytic approaches, one based on regression and one based on weighting are proposed to estimate the effect mediated through multiple mediators and the effects throu...

  7. Vibrational properties of amorphous semiconductors

    International Nuclear Information System (INIS)

    Schulz, P.A.B.

    1985-01-01

    A model for the lattice dynamics of a-Si 1-X N X is introduced. This model is based on a Born hamiltonian, solved in the Bethe lattice approximation. Starting from the local density of vibrational states, we analize the infrared absoption spectra of this material. (author) [pt

  8. Ultrafast vibrations of gold nanorings

    DEFF Research Database (Denmark)

    Kelf, T; Tanaka, Y; Matsuda, O

    2011-01-01

    We investigate the vibrational modes of gold nanorings on a silica substrate with an ultrafast optical technique. By comparison with numerical simulations, we identify several resonances in the gigahertz range associated with axially symmetric deformations of the nanoring and substrate. We...

  9. Monothiodibenzoylmethane: Structural and vibrational assignments

    DEFF Research Database (Denmark)

    Hansen, Bjarke Knud Vilster; Gorski, Alexander; Posokhov, Yevgen

    2007-01-01

    vibrational spectra were compared with theoretical transitions obtained with B3LYP/cc-pVTZ density functional theory (DFT). The results leave no doubt that the stable ground state configuration of TDBM corresponds to the intramolecularly hydrogen bonded enol form (e-CCC), and that the photoproduct corresponds...

  10. Low-Vibration Oscillating Compressor

    Science.gov (United States)

    Studer, P. A.

    1984-01-01

    Oscillating compressor momentum compensated: produces little vibration in its supporting structure. Compressure requires no lubrication and virtually free of wear. Compresses working fluids such as helium, nitrogen or chlorfluorocarbons for Stirling-cycle refrigeration or other purposes. Compressor includes two mutually opposed ferromagnetic pistons of same shape and mass. Electromagnetic flux links both pistons, causing magnetic attraction between them.

  11. Vibrational relaxation in OCS mixtures

    International Nuclear Information System (INIS)

    Simpson, C.J.S.M.; Gait, P.D.; Simmie, J.M.

    1976-01-01

    Experimental measurements are reported of vibrational relaxation times which may be used to show whether there is near resonant vibration-rotation energy transfer between OCS and H 2 , D 2 or HD. Vibrational relaxation times have been measured in OCS and OCS mixtures over the temperature range 360 to 1000 K using a shock tube and a laser schlieren system. The effectiveness of the additives in reducing the relaxation time of OCS is in the order 4 He 3 He 2 2 and HD. Along this series the effect of an increase in temperature changes from the case of speeding up the rate with 4 He to retarding it with D 2 , HD and H 2 . There is no measurable difference in the effectiveness of n-D 2 and o-D 2 and little, or no, difference between n-H 2 and p-H 2 . Thus the experimental results do not give clear evidence for rotational-vibration energy transfer between hydrogen and OCS. This contrasts with the situation for CO 2 + H 2 mixtures. (author)

  12. Vibrational entropies in metallic alloys

    Science.gov (United States)

    Ozolins, Vidvuds; Asta, Mark; Wolverton, Christopher

    2000-03-01

    Recently, it has been recognized that vibrational entropy can have significant effects on the phase stability of metallic alloys. Using density functional linear response calculations and molecular dynamics simulations we study three representative cases: (i) phase diagram of Al-rich Al-Sc alloys, (ii) stability of precipitate phases in CuAl_2, and (iii) phonon dynamics in bcc Zr. We find large vibrational entropy effects in all cases. In the Al-Sc system, vibrations increase the solid solubility of Sc in Al by decreasing the stability of the L12 (Al_3Sc) phase. This leads to a nearly ten-fold increase in the solid solubility of Sc in Al at T=800 K. In the Cu-Al system, our calculations predict that the tetragonal Laves phase of CuAl2 has 0.35 kB/atom higher vibrational entropy than the cubic CaF_2-type phase (the latter is predicted to be the T=0 K ground state of CuAl_2). This entropy difference causes a structural transformation in CuAl2 precipitates from the fluorite to the tetragonal Laves phase around T=500 K. Finally, we analyze the highly unusual dynamics of anharmonically stabilized bcc Zr, finding large diffuse-scattering intensity streaks between the bcc Bragg peaks.

  13. Ultrafast vibrations of gold nanorings

    DEFF Research Database (Denmark)

    Kelf, T; Tanaka, Y; Matsuda, O

    2011-01-01

    We investigate the vibrational modes of gold nanorings on a silica substrate with an ultrafast optical technique. By comparison with numerical simulations, we identify several resonances in the gigahertz range associated with axially symmetric deformations of the nanoring and substrate. We elucid...

  14. Effect of shelf aging on vibration transmissibility of anti-vibration gloves

    Science.gov (United States)

    SHIBATA, Nobuyuki

    2017-01-01

    Anti-vibration gloves have been used in real workplaces to reduce vibration transmitted through hand-held power tools to the hand. Generally materials used for vibration attenuation in gloves are resilient materials composed of certain synthetic and/or composite polymers. The mechanical characteristics of the resilient materials used in anti-vibration gloves are prone to be influenced by environmental conditions such as temperature, humidity, and photo-irradiation, which cause material degradation and aging. This study focused on the influence of shelf aging on the vibration attenuation performance of air-packaged anti-vibration gloves following 2 yr of shelf aging. Effects of shelf aging on the vibration attenuation performance of anti-vibration gloves were examined according to the Japan industrial standard JIS T8114 test protocol. The findings indicate that shelf aging induces the reduction of vibration attenuation performance in air-packaged anti-vibration gloves. PMID:28978817

  15. Experience in WWER fuel assemblies vibration analysis

    International Nuclear Information System (INIS)

    Ovtcharov, O.; Pavelko, V.; Usanov, A.; Arkadov, G.; Dolgov, A.; Molchanov, V.

    2003-01-01

    It is stated that the vibration studies of internals and the fuel assemblies should be conducted during the reactor designing, commissioning and commercial operation stages and the analysis methods being used should complement each other. The present paper describes the methods and main results of the vibration noise studies of internals and the fuel assemblies of the operating NPPs with WWER reactors, as an example of the implementation of the comprehensive approach to the analysis on equipment flow-induced vibration. At that, the characteristics of internals and fuel assemblies vibration loading were dealt jointly as they are elements of the same compound oscillating system and their vibrations have the interrelated nature

  16. Vibration isolation of a ship's seat

    Science.gov (United States)

    Agahi, Maryam; Samani, Mehrdad B.; Behzad, Mehdi

    2005-05-01

    Different factors cause vibration. These vibrations make the voyages difficult and reduce comfort and convenience in passenger ships. In this paper, the creating factors of vibration have discussed first, then with mathematical modelling it will be attempted to minimize the vibration over the crew's seat. The modelling consists of a system with two degrees of freedom and by using vibrationisolation with passive method of Tuned Mass Damper (TMD) it will be tried to reduce the vibration over personnel. Moreover using active control systems will be compared with passive systems.

  17. Control of pipe vibrations; Schwingungsminderung bei Rohrleitungen

    Energy Technology Data Exchange (ETDEWEB)

    Sinambari, G.R. [FH Bingen, Fachrichtung Umweltschutz, und IBS Ingenieurbuero fuer Schall- und Schwingungstechnik GmbH, Frankenthal (Germany); Thorn, U. [IBS Ingenieurbuero fuer Schall- und Schwingungstechnik GmbH, Frankenthal (Germany)

    2005-06-01

    Following commissioning of a new vacuum system for the refinery of MiRO Mineraloelraffinerie Oberrhein GmbH and Co. KG, vibrations occurred in the furnace exhaust pipes. As these had to be regarded as critical for the fatigue strength of the pipes, the pipes' vibration response in the critical frequency range was investigated immediately by means of a vibration analysis, and appropriate measures for vibration control were elaborated. All investigations, and the installation of the hydraulic vibration dampers, took place with the system operating. The effectiveness of the measures taken was checked by means of measurements following installation. The measures succeeded in attenuating the vibrations to a level at which, empirically, damage need no longer be expected. This paper illustrates the procedure for developing the vibration control measures and the essential results of the investigations. (orig.)

  18. Vibrations on board and health effects

    DEFF Research Database (Denmark)

    Jensen, Anker; Jepsen, Jørgen Riis

    2014-01-01

    There is only limited knowledge of the exposure to vibrations of ships’ crews and their risk of vibration-induced health effects. Exposure to hand-arm vibrations from the use of vibrating tools at sea does not differ from that in the land-based trades. However, in contrast to most other work places...... of the health consequences of whole body vibrations in land-transportation, such exposure at sea may affect ships’ passengers and crews. While the relation of back disorders to high levels of whole body vibration has been demonstrated among e.g. tractor drivers, there are no reported epidemiological evidence...... for such relation among seafarers except for fishermen, who, however, are also exposed to additional recognised physical risk factors at work. The assessment and reduction of vibrations by naval architects relates to technical implications of this impact for the ships’ construction, but has limited value...

  19. Interfacial instabilities in vibrated fluids

    Science.gov (United States)

    Porter, Jeff; Laverón-Simavilla, Ana; Tinao Perez-Miravete, Ignacio; Fernandez Fraile, Jose Javier

    2016-07-01

    Vibrations induce a range of different interfacial phenomena in fluid systems depending on the frequency and orientation of the forcing. With gravity, (large) interfaces are approximately flat and there is a qualitative difference between vertical and horizontal forcing. Sufficient vertical forcing produces subharmonic standing waves (Faraday waves) that extend over the whole interface. Horizontal forcing can excite both localized and extended interfacial phenomena. The vibrating solid boundaries act as wavemakers to excite traveling waves (or sloshing modes at low frequencies) but they also drive evanescent bulk modes whose oscillatory pressure gradient can parametrically excite subharmonic surface waves like cross-waves. Depending on the magnitude of the damping and the aspect ratio of the container, these locally generated surfaces waves may interact in the interior resulting in temporal modulation and other complex dynamics. In the case where the interface separates two fluids of different density in, for example, a rectangular container, the mass transfer due to vertical motion near the endwalls requires a counterflow in the interior region that can lead to a Kelvin-Helmholtz type instability and a ``frozen wave" pattern. In microgravity, the dominance of surface forces favors non-flat equilibrium configurations and the distinction between vertical and horizontal applied forcing can be lost. Hysteresis and multiplicity of solutions are more common, especially in non-wetting systems where disconnected (partial) volumes of fluid can be established. Furthermore, the vibrational field contributes a dynamic pressure term that competes with surface tension to select the (time averaged) shape of the surface. These new (quasi-static) surface configurations, known as vibroequilibria, can differ substantially from the hydrostatic state. There is a tendency for the interface to orient perpendicular to the vibrational axis and, in some cases, a bulge or cavity is induced

  20. Attitudes Toward, and Use of, Vibrators in China.

    Science.gov (United States)

    Jing, Shen; Lay, Alixe; Weis, Laura; Furnham, Adrian

    2018-01-02

    The current study examined the relationship between traditional masculine traits and attitudes toward vibrator use, actual vibrator use, and frequency of vibrator use in China. In all, 235 Chinese females aged between 16 and 58 years completed a questionnaire regarding attitudes toward, and personal use of, vibrators. The results showed a positive association between masculine traits and attitudes toward women's vibrator use, attitudes toward vibrator use and actual vibrator use, as well as frequency of vibrator use. The findings revealed an indirect path in which masculinity influences actual and frequency of vibrator use through attitudes toward women's vibrator use. Limitations and implications of the study are discussed.

  1. Dynamical response of vibrating ferromagnets

    CERN Document Server

    Gaganidze, E; Ziese, M

    2000-01-01

    The resonance frequency of vibrating ferromagnetic reeds in a homogeneous magnetic field can be substantially modified by intrinsic and extrinsic field-related contributions. Searching for the physical reasons of the field-induced resonance frequency change and to study the influence of the spin glass state on it, we have measured the low-temperature magnetoelastic behavior and the dynamical response of vibrating amorphous and polycrystalline ferromagnetic ribbons. We show that the magnetoelastic properties depend strongly on the direction of the applied magnetic field. The influence of the re-entrant spin glass transition on these properties is discussed. We present clear experimental evidence that for applied fields perpendicular to the main area of the samples the behavior of ferromagnetic reeds is rather independent of the material composition and magnetic state, exhibiting a large decrease of the resonance frequency. This effect can be very well explained with a model based on the dynamical response of t...

  2. A night with good vibrations

    CERN Multimedia

    2002-01-01

    Next week-end, the Geneva Science History Museum invites you to a Science Night under the banner of waves and vibrations. Scientists, artists and storytellers from more than forty institutes and local or regional associations will show that waves and vibrations form an integral part of our environment. You will be able to get in contact with the nature of waves through interactive exhibitions on sound and light and through hands-on demonstrations arranged in the Park of the Perle du Lac. On the CERN stand, you will be able to measure the speed of light with a bar of chocolate, and understand the scattering of waves with plastic ducks. Amazing, no? In addition to the stands, the Night will offer many other activities: reconstructions of experiments, a play, a concert of crystal glasses, an illuminated fountain, a house of spirits. More information Science Night, 6 and 7 July, Park of the Perle du Lac, Geneva

  3. Vibration of imperfect rotating disk

    Directory of Open Access Journals (Sweden)

    Půst L.

    2011-12-01

    Full Text Available This study is concerned with the theoretical and numerical calculations of the flexural vibrations of a bladed disk. The main focus of this study is to elaborate the basic background for diagnostic and identification methods for ascertaining the main properties of the real structure or an experimental model of turbine disks. The reduction of undesirable vibrations of blades is proposed by using damping heads, which on the experimental model of turbine disk are applied only on a limited number of blades. This partial setting of damping heads introduces imperfection in mass, stiffness and damping distribution on the periphery and leads to more complicated dynamic properties than those of a perfect disk. Calculation of FEM model and analytic—numerical solution of disk behaviour in the limited (two modes frequency range shows the splitting of resonance with an increasing speed of disk rotation. The spectrum of resonance is twice denser than that of a perfect disk.

  4. Vibrational communication of subterranean rodents

    OpenAIRE

    HROUZKOVÁ, Ema

    2012-01-01

    This PhD. thesis focuses on the vibrational communication of subterranean mammals, in particular, vocal communication of bathyergids (Heliophobius argenteocinereus, Fukomys mechowii, Fukomys darlingi) and seismic communication of Tachyoryctes. We recorded and analyzed the vocalization of three species and discussed the physical parameters of their vocalization in relationship to the special underground acoustic environment. Moreover, social systems of African mole-rats range from solitary to ...

  5. Tool-specific performance of vibration-reducing gloves for attenuating fingers-transmitted vibration

    Science.gov (United States)

    Welcome, Daniel E.; Dong, Ren G.; Xu, Xueyan S.; Warren, Christopher; McDowell, Thomas W.

    2016-01-01

    BACKGROUND Fingers-transmitted vibration can cause vibration-induced white finger. The effectiveness of vibration-reducing (VR) gloves for reducing hand transmitted vibration to the fingers has not been sufficiently examined. OBJECTIVE The objective of this study is to examine tool-specific performance of VR gloves for reducing finger-transmitted vibrations in three orthogonal directions (3D) from powered hand tools. METHODS A transfer function method was used to estimate the tool-specific effectiveness of four typical VR gloves. The transfer functions of the VR glove fingers in three directions were either measured in this study or during a previous study using a 3D laser vibrometer. More than seventy vibration spectra of various tools or machines were used in the estimations. RESULTS When assessed based on frequency-weighted acceleration, the gloves provided little vibration reduction. In some cases, the gloves amplified the vibration by more than 10%, especially the neoprene glove. However, the neoprene glove did the best when the assessment was based on unweighted acceleration. The neoprene glove was able to reduce the vibration by 10% or more of the unweighted vibration for 27 out of the 79 tools. If the dominant vibration of a tool handle or workpiece was in the shear direction relative to the fingers, as observed in the operation of needle scalers, hammer chisels, and bucking bars, the gloves did not reduce the vibration but increased it. CONCLUSIONS This study confirmed that the effectiveness for reducing vibration varied with the gloves and the vibration reduction of each glove depended on tool, vibration direction to the fingers, and finger location. VR gloves, including certified anti-vibration gloves do not provide much vibration reduction when judged based on frequency-weighted acceleration. However, some of the VR gloves can provide more than 10% reduction of the unweighted vibration for some tools or workpieces. Tools and gloves can be matched for

  6. Surveillance of vibrations in PWR

    International Nuclear Information System (INIS)

    Espefaelt, R.; Lorenzen, J.; Aakerhielm, F.

    1980-07-01

    The core of a PWR - including fuel elements, internal structure, control rods and core support structure inside the pressure vessel - is subjected to forces which can cause vibrations. One sensitive means to detect and analyse such vibrations is by means of the noise from incore and excore neutron detector signals. In this project noise recordings have been made on two occasions in the Ringhals 2 plant and the obtained data been analysed using the Studsvik Noise Analysis Program System (SNAPS). The results have been intepreted and a detailed description of the vibrational status of the core and pressure vessel internals has been produced. On the basis of the obtained results it is proposed that neutron signal noise analysis should be performed at each PWR plant in the beginning, middle and end of each fuel cycle and an analysis be made using the methods developed in the project. It would also provide a contribution to a higher degree of preparedness for diagnostic tasks in case of unexpected and abnormal events. (author)

  7. Complex Mediation

    DEFF Research Database (Denmark)

    Bødker, Susanne; Andersen, Peter Bøgh

    2005-01-01

    This article has its starting point in a large number of empirical findings regarding computer-mediated work. These empirical findings have challenged our understanding of the role of mediation in such work; on the one hand as an aspect of communication and cooperation at work and on the other hand...... as an aspect of human engagement with instruments of work. On the basis of previous work in activity-theoretical and semiotic human—computer interaction, we propose a model to encompass both of these aspects. In a dialogue with our empirical findings we move on to propose a number of types of mediation...... that have helped to enrich our understanding of mediated work and the design of computer mediation for such work....

  8. Attitudes Toward, and Use of, Vibrators in China

    OpenAIRE

    Jing, S.; Lay, A.; Weis, L.; Furnham, A.

    2018-01-01

    The current study examined the relationship between traditional masculine traits and attitudes toward vibrator use, actual vibrator use, and frequency of vibrator use in China. In all, 235 Chinese females aged between 16 and 58 years completed a questionnaire regarding attitudes toward, and personal use of, vibrators. The results showed a positive association between masculine traits and attitudes toward women's vibrator use, attitudes toward vibrator use and actual vibrator use, as well as f...

  9. Adaptive Piezoelectric Absorber for Active Vibration Control

    Directory of Open Access Journals (Sweden)

    Sven Herold

    2016-02-01

    Full Text Available Passive vibration control solutions are often limited to working reliably at one design point. Especially applied to lightweight structures, which tend to have unwanted vibration, active vibration control approaches can outperform passive solutions. To generate dynamic forces in a narrow frequency band, passive single-degree-of-freedom oscillators are frequently used as vibration absorbers and neutralizers. In order to respond to changes in system properties and/or the frequency of excitation forces, in this work, adaptive vibration compensation by a tunable piezoelectric vibration absorber is investigated. A special design containing piezoelectric stack actuators is used to cover a large tuning range for the natural frequency of the adaptive vibration absorber, while also the utilization as an active dynamic inertial mass actuator for active control concepts is possible, which can help to implement a broadband vibration control system. An analytical model is set up to derive general design rules for the system. An absorber prototype is set up and validated experimentally for both use cases of an adaptive vibration absorber and inertial mass actuator. Finally, the adaptive vibration control system is installed and tested with a basic truss structure in the laboratory, using both the possibility to adjust the properties of the absorber and active control.

  10. Ground test for vibration control demonstrator

    Science.gov (United States)

    Meyer, C.; Prodigue, J.; Broux, G.; Cantinaud, O.; Poussot-Vassal, C.

    2016-09-01

    In the objective of maximizing comfort in Falcon jets, Dassault Aviation is developing an innovative vibration control technology. Vibrations of the structure are measured at several locations and sent to a dedicated high performance vibration control computer. Control laws are implemented in this computer to analyse the vibrations in real time, and then elaborate orders sent to the existing control surfaces to counteract vibrations. After detailing the technology principles, this paper focuses on the vibration control ground demonstration that was performed by Dassault Aviation in May 2015 on Falcon 7X business jet. The goal of this test was to attenuate vibrations resulting from fixed forced excitation delivered by shakers. The ground test demonstrated the capability to implement an efficient closed-loop vibration control with a significant vibration level reduction and validated the vibration control law design methodology. This successful ground test was a prerequisite before the flight test demonstration that is now being prepared. This study has been partly supported by the JTI CleanSky SFWA-ITD.

  11. Vibration-type particle separation device with piezoceramic vibrator

    Science.gov (United States)

    Ooe, Katsutoshi; Doi, Akihiro

    2008-12-01

    During hemanalysis, it is necessary to separate blood cells from whole blood. Many blood separation methods, for example, centrifugation and filtering, are in practical use. However, the use of these methods involves problems from the perspectives of processing speed and processing volume. We develop new types of blood separation devices that use piezo-ceramic vibrators. The first device uses a capillary. One end of the capillary is fixed to the device frame, and the other is fixed to a piezo-ceramic vibrator. The vibrator transmits bending waves to the capillary. This device can process only a small amount of solution; therefore, it is not suitable for hemanalysis. In order to solve this problem, we developed a second device; this device has a pair of thin glass plates with a small gap as a substitute for the capillary used in the first device. These devices are based on the fact that particles heavier than water move toward transverse velocity antinodes while those lighter than water move toward velocity nodes. In this report, we demonstrate the highspeed separation of silica microbeads and 50-vol% glycerol water by using these devices. The first device can separate the abovementioned solution within 3 min while the second can separate it within 1 min. Both devices are driven by a rectangular wave of 15 to 20 Vpp. Furthermore, it has been confirmed that red blood cells are separated from diluted whole blood using the first device within approximately 1 min. These devices have transparency, so they can compose as the analysis system with the chemical analyzer easily.

  12. Identification of Bearing Failure Using Signal Vibrations

    Science.gov (United States)

    Yani, Irsyadi; Resti, Yulia; Burlian, Firmansyah

    2018-04-01

    Vibration analysis can be used to identify damage to mechanical systems such as journal bearings. Identification of failure can be done by observing the resulting vibration spectrum by measuring the vibration signal occurring in a mechanical system Bearing is one of the engine elements commonly used in mechanical systems. The main purpose of this research is to monitor the bearing condition and to identify bearing failure on a mechanical system by observing the resulting vibration. Data collection techniques based on recordings of sound caused by the vibration of the mechanical system were used in this study, then created a database system based bearing failure due to vibration signal recording sounds on a mechanical system The next step is to group the bearing damage by type based on the databases obtained. The results show the percentage of success in identifying bearing damage is 98 %.

  13. Unjamming a granular hopper by vibration

    Science.gov (United States)

    Janda, A.; Maza, D.; Garcimartín, A.; Kolb, E.; Lanuza, J.; Clément, E.

    2009-07-01

    We present an experimental study of the outflow of a hopper continuously vibrated by a piezoelectric device. Outpouring of grains can be achieved for apertures much below the usual jamming limit observed for non-vibrated hoppers. Granular flow persists down to the physical limit of one grain diameter, a limit reached for a finite vibration amplitude. For the smaller orifices, we observe an intermittent regime characterized by alternated periods of flow and blockage. Vibrations do not significantly modify the flow rates both in the continuous and the intermittent regime. The analysis of the statistical features of the flowing regime shows that the flow time significantly increases with the vibration amplitude. However, at low vibration amplitude and small orifice sizes, the jamming time distribution displays an anomalous statistics.

  14. Cleaning device for vibrational hose filter

    Energy Technology Data Exchange (ETDEWEB)

    Engels, R

    1978-01-05

    Filter hoses out of web in dust separators can be cleaned by enforced vibrations. The efficiency of the cleaning is a maximum if the vibrations are at about the individual frequency of the whole arrangement. In the interior of the hose a cage from bars parallel to the wall of the hose is placed on its total length. The bars are fixed at one end and connected with a vibration exciter at the other end. The unilaterally fixed vibration bars can be adjusted to the individual frequency of the vibration exciter. If the hose filter is flown through from the outer to the inner side the vibration bars serve as a supporting body. In the reverse case the bars are placed on the outer side of the hose filter.

  15. Research In Diagnosing Bearing Defects From Vibrations

    Science.gov (United States)

    Zoladz, T.; Earhart, E.; Fiorucci, T.

    1995-01-01

    Report describes research in bearing-defect signature analysis - use of vibration-signal analysis to diagnose defects in roller and ball bearings. Experiments performed on bearings in good condition and other bearings in which various parts scratched to provide known defects correlated with vibration signals. Experiments performed on highly instrumented motor-driven rotor assembly at speeds up to 10,050 r/min, using accelerometers, velocity probes, and proximity sensors mounted at various locations on assembly to measure vibrations.

  16. Theory And Working Of Noise And Vibration

    International Nuclear Information System (INIS)

    Jeong, Il Rok

    1988-09-01

    This book deals with theory of noise including physical property of noise like term and characteristic of sound, occurrence of sound, characteristic of noise pollution and main cause of occurrence of noise, technique of prevention of noise with noise reduction, construction guide for prevention of noise, and measure of interior noise. It also has the theory of vibration such as an introduction of vibration, and technology of prevention of vibration, official test method of environmental pollution, and summary of protection of the environment.

  17. First international conference on vibration control in optics and metrology

    International Nuclear Information System (INIS)

    Baker, L.R.

    1987-01-01

    This book contains 27 selections. Some of the titles are: Use of optics for vibration analysis of automotive components; Use of pulsed lasers for vibration analysis in the nuclear power industry; Vibration analysis of photocopiers; Control of ground vibrations; Design of low-vibration buildings: two case histories; and Continuous pulsed electronic speckle pattern interferometry

  18. Developed vibration waveform monitoring unit for CBM

    International Nuclear Information System (INIS)

    Hamada, T.; Hotsuta, K.; Hirose, I.; Morita, E.

    2007-01-01

    In nuclear power plants, many rotating machines such as pumps and fans are in use. Shikoku Research Institute Inc. has recently developed easy-to-use tools to facilitate the maintenance of such equipment. They include a battery-operated vibration waveform monitoring unit which allows unmanned vibration monitoring on a regular basis and data collection even from intermittently operating equipment, a waveform data collector which can be used for easy collection, storage, control, and analysis of raw vibration waveform data during normal operation, and vibration analysis and evaluation tools. A combination of these tools has a high potential for optimization of rotating equipment maintenance. (author)

  19. Electromagnetic Vibration Energy Harvesting for Railway Applications

    Directory of Open Access Journals (Sweden)

    Bradai S.

    2018-01-01

    Full Text Available Safe localization of trains via GPS and wireless sensors is essential for railway traffic supervision. Especially for freight trains and because normally no power source is available on the wagons, special solutions for energy supply have to be developed based on energy harvesting techniques. Since vibration is available in this case, it provides an interesting source of energy. Nevertheless, in order to have an efficient design of the harvesting system, the existing vibration needs to be investigated. In this paper, we focus on the characterization of vibration parameters in railway application. We propose an electromagnetic vibration converter especially developed to this application. Vibration profiles from a train traveling between two German cities were measured using a data acquisition system installed on the train’s wagon. Results show that the measured profiles present multiple frequency signals in the range of 10 to 50 Hz and an acceleration of up to 2 g. A prototype for a vibration converter is designed taking into account the real vibration parameters, robustness and integrability requirements. It is based on a moving coil attached to a mechanical spring. For the experimental emulation of the train vibrations, a shaker is used as an external artificial vibration source controlled by a laser sensor in feedback. A maximum voltage of 1.7 V peak to peak which corresponds to a maximum of 10 mW output power where the applied excitation frequency is close to the resonant frequency of the converter which corresponds to 27 Hz.

  20. The Efficacy of Anti-vibration Gloves

    Science.gov (United States)

    Hewitt, Sue; Dong, Ren; McDowell, Tom; Welcome, Daniel

    2016-01-01

    Anyone seeking to control the risks from vibration transmitted to the hands and arms may contemplate the use of anti-vibration gloves. To make an informed decision about any type of personal protective equipment, it is necessary to have performance data that allow the degree of protection to be estimated. The information provided with an anti-vibration glove may not be easy to understand without some background knowledge of how gloves are tested and does not provide any clear route for estimating likely protection. Some of the factors that influence the potential efficacy of an anti-vibration glove include how risks from hand–arm vibration exposure are assessed, how the standard test for a glove is carried out, the frequency range and direction of the vibration for which protection is sought, how much hand contact force or pressure is applied and the physical limitations due to glove material and construction. This paper reviews some of the background issues that are useful for potential purchasers of anti-vibration gloves. Ultimately, anti-vibration gloves cannot be relied on to provide sufficient and consistent protection to the wearer and before their use is contemplated all other available means of vibration control ought first to be implemented. PMID:27582615

  1. Axisymmetric vibrations of thick shells of revolution

    International Nuclear Information System (INIS)

    Suzuki, Katsuyoshi; Kosawada, Tadashi; Takahashi, Shin

    1983-01-01

    Axisymmetric shells of revolution are used for chemical plants, nuclear power plants, aircrafts, structures and so on, and the elucidation of their free vibration is important for the design. In this study, the axisymmetric vibration of a barrel-shaped shell was analyzed by the modified thick shell theory. The Lagrangian during one period of the vibration of a shell of revolution was determined, and from its stopping condition, the vibration equations and the boundary conditions were derived. The vibration equations were analyzed strictly by using the series solution. Moreover, the basic equations for the strain of a shell and others were based on those of Love. As the examples of numerical calculation, the natural frequency and vibration mode of the symmetrical shells of revolution fixed at both ends and supported at both ends were determined, and their characteristics were clarified. By comparing the results of this study with the results by thin shell theory, the effects of shearing deformation and rotary inertia on the natural frequency and vibration mode were clarified. The theoretical analysis and the numerical calculation are described. The effects of shearing deformation and rotary inertia on the natural frequency became larger in the higher order vibration. The vibration mode did not much change in both theories. (Kako, I.)

  2. Aircraft gas turbine engine vibration diagnostics

    Directory of Open Access Journals (Sweden)

    Stanislav Fábry

    2017-11-01

    Full Text Available In the Czech and Slovak aviation are in service elderly aircrafts, usually produced in former Soviet Union. Their power units can be operated in more efficient way, in case of using additional diagnostic methods that allow evaluating their health. Vibration diagnostics is one of the methods indicating changes of rotational machine dynamics. Ground tests of aircraft gas turbine engines allow vibration recording and analysis. Results contribute to airworthiness evaluation and making corrections, if needed. Vibration sensors distribution, signal recording and processing are introduced in a paper. Recorded and re-calculated vibration parameters are used in role of health indicators.

  3. Flow induced vibrations of piping

    International Nuclear Information System (INIS)

    Gibert, R.J.; Axisa, F.

    1977-01-01

    In order to design the supports of piping systems, estimations of the vibrations induced by the fluid conveyed through the pipes are generally needed. For that purpose it is necessary to calculate the model parameters of liquid containing pipes. In most computer codes, fluid effects are accounted for just by adding the fluid mass to the structure. This may lead to serious errors. This paper presents a method to take into account these effects, by solving a coupled mechanical-acoustical problem: the computer code TEDEL of the C.E.A /D.E.M.T. System, based on the finite-elements method, has been extended to calculate simultaneously the pressure fluctuations in the fluid and the vibrations of the pipe. By this way the mechanical-acoustical coupled eigenmodes of any piping system can be obtained. These eigenmodes are used to determine the response of the system to various sources. Equations have been written in the hypohesis that acoustical wave lengths remain large compared to the diameter of the pipe. The method has been checked by an experiment performed on the GASCOGNE loop at D.E.M.T. The piping system under test consists of a tube with four elbows. The circuit is ended at each extremity by a large vessel which performs acoustical isolation by generating modes for the pressure. Excitation of the circuit is caused by a valve located near the downstream vessel. This provides an efficient localised broad band acoustical source. The comparison between the test results and the calculations has shown that the low frequency resonant characteristics of the pipe and the vibrational amplitude at various flow-rates can be correctly predicted

  4. EMBEDDED SYSTEMS FOR VIBRATION MONITORING

    Directory of Open Access Journals (Sweden)

    Miloš Milovančević

    2014-08-01

    Full Text Available The purpose of the research presented in this paper is the development of the optimal micro configuration for vibration monitoring of pumping aggregate, based on Microchip’s microcontroller (MC. Hardware used is 10-bit MC, upgraded with 12/bit A/D converter. Software for acquisition and data analysis is optimized for testing turbo pumps with rotation speed up to 2000 rpm. This software limitation is set for automatic diagnostics and for individual and manual vibro-diagnostic; the only limitation is set by accelerometer performance. The authors have performed numerous measurements on a wide range of turbo aggregates for establishing the operational condition of pumping aggregates.

  5. Introduction to vibrations and waves

    CERN Document Server

    Pain, H John

    2015-01-01

    Based on the successful multi-edition book "The Physics ofVibrations and Waves" by John Pain, the authors carry overthe simplicity and logic of the approach taken in the originalfirst edition with its focus on the patterns underlying andconnecting so many aspects of physical behavior, whilst bringingthe subject up-to-date so it is relevant to teaching in the21st century.The transmission of energy by wave propagation is a key conceptthat has applications in almost every branch of physics withtransmitting mediums essentially acting as a continuum of coupledoscillators. The characterization of t

  6. Vibration diagnostics instrumentation for ILC

    Energy Technology Data Exchange (ETDEWEB)

    Bertolini, A.

    2007-06-15

    The future e{sup -}e{sup +} 500 GeV International Linear Collider will rely on unprecedented nanometer scale particle beam size at the interaction point, in order to achieve the design luminosity. Tight tolerances on static and dynamic alignment of the accelerator cavities and optical components are demanded to transport and focus the high energy electron and positron beams with reasonable position jitter and low emittance. A brief review of techniques and devices evaluated and developed so far for the vibration diagnostics of the machine is presented in this paper. (orig.)

  7. Vibrational Spectroscopy of Chromatographic Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Jeanne E. Pemberton

    2011-03-10

    Chromatographic separations play a central role in DOE-supported fundamental research related to energy, biological systems, the environment, and nuclear science. The overall portfolio of research activities in the Separations and Analysis Program within the DOE Office of Basic Energy Sciences includes support for activities designed to develop a molecular-level understanding of the chemical processes that underlie separations for both large-scale and analytical-scale purposes. The research effort funded by this grant award was a continuation of DOE-supported research to develop vibrational spectroscopic methods to characterize the interfacial details of separations processes at a molecular level.

  8. Wideband Piezomagnetoelastic Vibration Energy Harvesting

    DEFF Research Database (Denmark)

    Lei, Anders; Thomsen, Erik Vilain

    2014-01-01

    This work presents a small-scale wideband piezomagnetoelastic vibration energy harvester (VEH) aimed for operation at frequencies of a few hundred Hz. The VEH consists of a tape-casted PZT cantilever with thin sheets of iron foil attached on each side of the free tip. The wideband operation...... is achieved by placing the cantilever in a magnetic field induced by either one or two magnets located oppositely of the cantilever. The attraction force created by the magnetic field and iron foils introduces a mechanical force in opposite direction of the cantilevers restoring force causing a spring...

  9. Vibration diagnostics instrumentation for ILC

    International Nuclear Information System (INIS)

    Bertolini, A.

    2007-06-01

    The future e - e + 500 GeV International Linear Collider will rely on unprecedented nanometer scale particle beam size at the interaction point, in order to achieve the design luminosity. Tight tolerances on static and dynamic alignment of the accelerator cavities and optical components are demanded to transport and focus the high energy electron and positron beams with reasonable position jitter and low emittance. A brief review of techniques and devices evaluated and developed so far for the vibration diagnostics of the machine is presented in this paper. (orig.)

  10. Multivariate Analysis of Ladle Vibration

    Science.gov (United States)

    Yenus, Jaefer; Brooks, Geoffrey; Dunn, Michelle

    2016-08-01

    The homogeneity of composition and uniformity of temperature of the steel melt before it is transferred to the tundish are crucial in making high-quality steel product. The homogenization process is performed by stirring the melt using inert gas in ladles. Continuous monitoring of this process is important to make sure the action of stirring is constant throughout the ladle. Currently, the stirring process is monitored by process operators who largely rely on visual and acoustic phenomena from the ladle. However, due to lack of measurable signals, the accuracy and suitability of this manual monitoring are problematic. The actual flow of argon gas to the ladle may not be same as the flow gage reading due to leakage along the gas line components. As a result, the actual degree of stirring may not be correctly known. Various researchers have used one-dimensional vibration, and sound and image signals measured from the ladle to predict the degree of stirring inside. They developed online sensors which are indeed to monitor the online stirring phenomena. In this investigation, triaxial vibration signals have been measured from a cold water model which is a model of an industrial ladle. Three flow rate ranges and varying bath heights were used to collect vibration signals. The Fast Fourier Transform was applied to the dataset before it has been analyzed using principal component analysis (PCA) and partial least squares (PLS). PCA was used to unveil the structure in the experimental data. PLS was mainly applied to predict the stirring from the vibration response. It was found that for each flow rate range considered in this study, the informative signals reside in different frequency ranges. The first latent variables in these frequency ranges explain more than 95 pct of the variation in the stirring process for the entire single layer and the double layer data collected from the cold model. PLS analysis in these identified frequency ranges demonstrated that the latent

  11. CRBRP flow induced vibration program

    Energy Technology Data Exchange (ETDEWEB)

    Novendstern, E H [Westinghouse Advanced Reactor Division, Madison, PA (United States); Grochowski, F A; Yang, T M [General Electric Co., Fast Breeder Reactor Department, Sunnyvale, CA (United States); Ryan, J A; Mulcahy, T M

    1977-12-01

    The program to assure the structural adequacy of Clinch River Breeder Reactor (CRBRP) components during its planned 30 years of operation is described. The program includes (1) an assessment of reactor components relative to their susceptibility to FIV, (2) designing to minimize component excitation due to Fluid induced vibrations (FIV), (3) scale model tests to measure structural response during simulated operating conditions and (4) preoperational tests. An overview of the CRBRP test program is described. Additionally, details of scale model testing of reactor internals and the steam generator is described in more detail. (author)

  12. Adaptive photodetectors for vibration monitoring

    International Nuclear Information System (INIS)

    Sokolov, I.A.

    2003-01-01

    We present characteristics of laser vibrometer using semiconductor GaAs and molecular SnS 2 adaptive photodetectors (AP) based on the effect of the non-steady-state photoelectromotive force. AP enable efficient direct conversion of high-frequency phase modulation of speckle-like optical wave reflected from the vibrating object into an output electrical signal with concomitant setting of optimal operation point of the interferometer and suppression of amplitude laser noise. The sensitivity of the setup is analyzed and further improvements in operation of AP are discussed

  13. Semiclassical theory of plate vibrations

    International Nuclear Information System (INIS)

    Bogomolny, E.; Hugues, E.

    1996-11-01

    The bi-harmonic equation of flexural vibrations of elastic plates is studied by a semiclassical method which can easily be generalized for other models of wave propagation. The surface and perimeter terms of the asymptotic number of levels are derived exactly. The next constant term is also derived. A semiclassical approximation of the quantization condition is obtained. A Berry-Tabor formula and a Gutzwiller trace formula are deduced for the integrable and chaotic cases respectively. From 600 eigenvalues of a clamped stadium plate obtained by a specially developed numerical algorithm, the trace formula is assessed, looking at its Fourier transform compared with the membrane case. (author)

  14. Collective vibrational spectra of α- and γ-glycine studied by terahertz and Raman spectroscopy

    International Nuclear Information System (INIS)

    Shi Yulei; Wang Li

    2005-01-01

    Terahertz time-domain spectroscopy is used to investigate the absorption and dispersion of polycrystalline α- and γ-glycine in the spectral region 0.5-3.0 THz. The spectra exhibit distinct features in these two crystalline phases. The observed far-infrared responses are attributed to intermolecular vibrational modes mediated by hydrogen bonds. We also measure the Raman spectra of the polycrystalline and dissolved glycine in the frequency range 28-3900 cm -1 . The results show that all the vibrational modes below 200 cm -1 are nonlocalized but are of a collective (phonon-like) nature. Furthermore, the temperature dependence of the Raman spectra of α-glycine agrees with the anharmonicity mechanism of the vibrational potentials

  15. Flow induced vibrations of piping

    International Nuclear Information System (INIS)

    Gibert, R.J.; Axisa, F.

    1977-01-01

    In order to design the supports of piping systems, estimations of the vibrations induced by the fluid conveyed through the pipes are generally needed. For that purpose it is necessary to calculate the model parameters of liquid containing pipes. In most computer codes, fluid effects are accounted for just by adding the fuid mass to the structure. This may lead to serious errors.- Inertial effects from the fluid are not correctly evaluated especially in the case of bended or of non-uniform section pipes. Fluid boundary conditions are simply ignored. - In many practical problems fluid compressibility cannot be negelcted, even in the low frequencies domain which corresponds to efficient excitation by turbulent sources of the flow. This paper presents a method to take into account these efects, by solving a coupled mechanical acoustical problem: the computer code TEDEL of the C.E.A./D.E.M.T. System, based on the finite-elements method, has been extended to calculate simultaneously the pressure fluctuations in the fluid and the vibrations of the pipe. (Auth.)

  16. AVM branch vibration test equipment

    International Nuclear Information System (INIS)

    Anne, J.P.

    1995-01-01

    An inventory of the test equipment of the AVM Branch ''Acoustic and Vibratory Mechanics Analysis Methods'' group has been undertaken. The purpose of this inventory is to enable better acquaintance with the technical characteristics of the equipment, providing an accurate definition of their functionalities, ad to inform potential users of the possibilities and equipment available in this field. The report first summarizes the various experimental surveys conduced. Then, using the AVM equipment database to draw up an exhaustive list of available equipment, it provides a full-scope picture of the vibration measurement systems (sensors, conditioners and exciters) and data processing resources commonly used on industrial sites and in laboratories. A definition is also given of a mobile test unit, called 'shelter', and a test bench used for the testing and performance rating of the experimental analysis methods developed by the group. The report concludes with a description of two fixed installations: - the calibration bench ensuring the requisite quality level for the vibration measurement systems ; - the training bench, whereby know-how acquired in the field in the field of measurement and experimental analysis processes is made available to others. (author). 27 refs., 15 figs., 2 appends

  17. Coherent lattice vibrations in superconductors

    International Nuclear Information System (INIS)

    Kadin, Alan M.

    2008-01-01

    A recent analysis has shown that the pair wavefunction within the BCS theory may be represented in real-space as a spherical electronic orbital (on the scale of the coherence length ξ 0 ) coupled to a standing-wave lattice vibration with wavevector 2k F and a near-resonant phonon frequency. The present paper extends this picture to a coherent pattern of phonon standing-waves on the macroscopic scale, with electrons forming Bloch waves and an energy gap much like those in the classic band theory of crystals. These parallel planes form a diffractive waveguide permitting electron waves to traveling parallel to the planes, corresponding to lossless supercurrent. A similar picture may be extended to unconventional superconductors such as the cuprates, with an array of standing spin waves rather than phonons. Such coherent lattice vibrations should be universal indicators of the superconducting state, and should be observable below T c using X-ray and neutron diffraction techniques. Further implications of this picture are discussed

  18. Noise and vibration analysis system

    International Nuclear Information System (INIS)

    Johnsen, J.R.; Williams, R.L.

    1985-01-01

    The analysis of noise and vibration data from an operating nuclear plant can provide valuable information that can identify and characterize abnormal conditions. Existing plant monitoring equipment, such as loose parts monitoring systems (LPMS) and neutron flux detectors, may be capable of gathering noise data, but may lack the analytical capability to extract useful meanings hidden in the noise. By analyzing neutron noise signals, the structural motion and integrity of core components can be assessed. Computer analysis makes trending of frequency spectra within a fuel cycle and from one cycle to another a practical means of core internals monitoring. The Babcock and Wilcox Noise and Vibration Analysis System (NVAS) is a powerful, compact system that can automatically perform complex data analysis. The system can acquire, process, and store data, then produce report-quality plots of the important parameter. Software to perform neutron noise analysis and loose parts analysis operates on the same hardware package. Since the system is compact, inexpensive, and easy to operate, it allows utilities to perform more frequency analyses without incurring high costs and provides immediate results

  19. Time-resolved vibrational spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Tokmakoff, Andrei [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Champion, Paul [Northeastern Univ., Boston, MA (United States); Heilweil, Edwin J. [National Inst. of Standards and Technology (NIST), Boulder, CO (United States); Nelson, Keith A. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Ziegler, Larry [Boston Univ., MA (United States)

    2009-05-14

    This document contains the Proceedings from the 14th International Conference on Time-Resolved Vibrational Spectroscopy, which was held in Meredith, NH from May 9-14, 2009. The study of molecular dynamics in chemical reaction and biological processes using time-resolved spectroscopy plays an important role in our understanding of energy conversion, storage, and utilization problems. Fundamental studies of chemical reactivity, molecular rearrangements, and charge transport are broadly supported by the DOE's Office of Science because of their role in the development of alternative energy sources, the understanding of biological energy conversion processes, the efficient utilization of existing energy resources, and the mitigation of reactive intermediates in radiation chemistry. In addition, time-resolved spectroscopy is central to all fiveof DOE's grand challenges for fundamental energy science. The Time-Resolved Vibrational Spectroscopy conference is organized biennially to bring the leaders in this field from around the globe together with young scientists to discuss the most recent scientific and technological advances. The latest technology in ultrafast infrared, Raman, and terahertz spectroscopy and the scientific advances that these methods enable were covered. Particular emphasis was placed on new experimental methods used to probe molecular dynamics in liquids, solids, interfaces, nanostructured materials, and biomolecules.

  20. Impact self-excited vibrations of linear motor

    Science.gov (United States)

    Zhuravlev, V. Ph.

    2010-08-01

    Impact self-exciting vibration modes in a linear motor of a monorail car are studied. Existence and stability conditions of self-exciting vibrations are found. Ways of avoiding the vibrations are discussed.

  1. Once upon Anion: A Tale of Photodetachment

    Science.gov (United States)

    Lineberger, W. Carl

    2013-04-01

    This contribution is very much a personal history of a journey through the wonderful world of anion chemistry, and a tale of how advances in laser technologies, theoretical methods, and computational capabilities continuously enabled advances in our understanding. It is a story of the excitement and joy that come from the opportunity to add to the fabric of science, and to do so by working as a group of excited explorers with common goals. The participants in this journey include me, my students and postdoctoral associates, my collaborators, and our many generous colleagues. It all happened, in the words of the Beatles, “with a little help from my friends.” Actually, it was so much more than a little help!

  2. Multiquanta photodetachment from the H- ion

    International Nuclear Information System (INIS)

    Tang, Chen-Yau.

    1992-03-01

    Multiphoton detachment (MPD) of an electron from the loosely bound H - system (binding energy = 0.7542 eV) has been studied at various photon energies and laser intensities. In the center of mass of 800-MeV H - ions the CO 2 laser photon energy, 0.117 eV, was Doppler tuned over a wide range, from 0.15 to 0.39 eV. The peak laser intensity in the lab frame was varied from 2 to 12 GW/cm 2 . The general behavior of MPD versus photon energy and the ac-Stark/pondermotive effects are of special interest in the study. Characteristic threshold structures by absorption of 2, 3, 4, and 5 photons were observed, as evidenced by rapid changes in the signal amplitudes. These thresholds provide a straightforward picture of channel opening in MPD as the photon energy is increased. A fit of two-photon detachment data to the Wigner threshold law showed a good match with a small intensity-induced shift in the threshold energy. A study of laser intensity effects demonstrated departures from the simple power law predicted by lowest-order perturbation theory, which is possibly another indication of pondermotive shifts in the threshold. The absolute MPD rates have been estimated and found to be in fairly good agreement with the results of Floquet theory

  3. Recent advances in micro-vibration isolation

    Science.gov (United States)

    Liu, Chunchuan; Jing, Xingjian; Daley, Steve; Li, Fengming

    2015-05-01

    Micro-vibration caused by disturbance sources onboard spacecraft can severely degrade the working environment of sensitive payloads. Some notable vibration control methods have been developed particularly for the suppression or isolation of micro-vibration over recent decades. Usually, passive isolation techniques are deployed in aerospace engineering. Active isolators, however, are often proposed to deal with the low frequency vibration that is common in spacecraft. Active/passive hybrid isolation has also been effectively used in some spacecraft structures for a number of years. In semi-active isolation systems, the inherent structural performance can be adjusted to deal with variation in the aerospace environment. This latter approach is potentially one of the most practical isolation techniques for micro-vibration isolation tasks. Some emerging advanced vibration isolation methods that exploit the benefits of nonlinearity have also been reported in the literature. This represents an interesting and highly promising approach for solving some challenging problems in the area. This paper serves as a state-of-the-art review of the vibration isolation theory and/or methods which were developed, mainly over the last decade, specifically for or potentially could be used for, micro-vibration control.

  4. Vibrational measurements in 3-ID-B

    International Nuclear Information System (INIS)

    Sutter, J.; Alp, E.; Barraza, J.; Shu, D.

    1998-04-01

    The authors have undertaken a series of vibrational measurements in hutch 3-ID-B. Their motivation was to compare two different methods of mounting an interferometer for effectiveness in vibrational isolation and stability. In addition they were able to compare the stability of the optical table with and without its eight large bolts inserted

  5. General vibration monitoring: Utility Building, August 1992

    International Nuclear Information System (INIS)

    Jendrzejczyk, J.A.; Wambsganss, M.W.; Smith, R.K.

    1993-01-01

    This vibration data was generated from measurements made on 8/12/92. The contents are self explanatory. They are baseline measurements and no exceptionally large vibration amplitude or response was observed. These measurements represent baseline measurements, i.e., measurements with no driving forces active, made on the utility building, a service building for the Advanced Photon Source at Argonne National Laboratory

  6. Dissimilar Dynamics of Coupled Water Vibrations

    NARCIS (Netherlands)

    Jansen, Thomas L. C.; Cringus, Dan; Pshenichnikov, Maxim S.

    2009-01-01

    Dissimilar dynamics of coupled stretch vibrations of a water molecule are revealed by two-dimensional, IR correlation spectroscopy. These are caused by essentially non-Gaussian fluctuations of the electric field exerted by the environment on the individual OH stretch vibrations. Non-Gaussian

  7. Experimental evaluation of vibrations in heat exchangers

    International Nuclear Information System (INIS)

    Martin Ghiselli, A.

    1997-01-01

    Flow induced vibrations may produce damage of heat exchangers, condensers and steam generators tubes. To evaluate this problem a set of tests were developed to know the real support state of the tubes, which have great influence on the vibration response. This paper include a description of the tests and the results obtained applying them on a heat exchanger equipment. (author) [es

  8. Multipole pair vibrations in superfluid 3He

    International Nuclear Information System (INIS)

    Baldo, M.; Giansiracusa, G.; Lombardo, U.; Pucci, R.; Petronio, G.

    1978-01-01

    Starting from a path integral formation of the 3 He superfluidity, the authors study the pair vibrations around the BCS solution. For both the BW and ABM states get a set of possible excitations. In particular it is shown that a new type of excitation is present for pure 1 = 2 spin singlet vibration. (Auth.)

  9. Vibrations in pipelines of nuclear power plants

    International Nuclear Information System (INIS)

    Leal, M.R.L.V.; Bevilacqua, L.

    1984-01-01

    It is presented the main causes of vibrations in nuclear power plants pipelines to allow the identification of critical areas and correct the errors during the specification design. The methods of vibration analysis to give subsidies in the determination of the corrective providences when the problem appears during the commissioning or the generation energy, are also presented. (M.C.K.) [pt

  10. 14 CFR 33.43 - Vibration test.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Vibration test. 33.43 Section 33.43... STANDARDS: AIRCRAFT ENGINES Block Tests; Reciprocating Aircraft Engines § 33.43 Vibration test. (a) Each... configuration of the propeller type which is used for the endurance test, and using, for other engines, the same...

  11. 14 CFR 33.83 - Vibration test.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Vibration test. 33.83 Section 33.83... STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.83 Vibration test. (a) Each engine... experience, analysis, and component test and shall address, as a minimum, blades, vanes, rotor discs, spacers...

  12. Axisymmetric vibrations of thin shells of revolution

    International Nuclear Information System (INIS)

    Suzuki, Katsuyoshi; Kikuchi, Norio; Kosawada, Tadashi; Takahashi, Shin

    1983-01-01

    The problem of free vibration of axisymmetric shells of revolution is important in connection with the design of pressure vessels, chemical equipment, aircrafts, structures and so on. In this study, the axisymmetrical vibration of a thin shell of revolution having a constant curvature in meridian direction was analyzed by thin shell theory. First, the Lagrangian during one period of the vibration of a shell of revolution was determined by the primary approximate theory of Love, and the vibration equations and boundary conditions were derived from its stopping condition. The vibration equations were strictly analyzed by using the series solution. The basic equations for the strain and strain energy of a shell were based on those of Novozhilov. As the examples of numerical calculation, the natural frequency and vibration mode of the symmetrical shells of revolution fixed at both ends and supported at both ends were determined, and their characteristics were clarified. The theory and the numerical calculation ore described. Especially in the frequency curves, the waving phenomena were observed frequently, which were not seen in non-axisymmetric vibration, accordingly also the vibration mode changed in complex state on the frequency curves of same order. The numerical calculation was carried out in the large computer center in Tohoku University. (Kako, I.)

  13. Adaptive techniques for diagnostics of vibrating structures

    International Nuclear Information System (INIS)

    Skormin, V.A.; Sankar, S.

    1983-01-01

    An adaptive diagnostic procedure for vibrating structures based on correspondence between current estimates of stiffness matrix and structure status is proposed. Procedure employs adaptive mathematical description of the vibrating structure in frequency domain, statistical techniques for detection and location of changes of structure properties, 'recognition' and prediction of defects. (orig.)

  14. Benefits of Spacecraft Level Vibration Testing

    Science.gov (United States)

    Gordon, Scott; Kern, Dennis L.

    2015-01-01

    NASA-HDBK-7008 Spacecraft Level Dynamic Environments Testing discusses the approaches, benefits, dangers, and recommended practices for spacecraft level dynamic environments testing, including vibration testing. This paper discusses in additional detail the benefits and actual experiences of vibration testing spacecraft for NASA Goddard Space Flight Center (GSFC) and Jet Propulsion Laboratory (JPL) flight projects. JPL and GSFC have both similarities and differences in their spacecraft level vibration test approach: JPL uses a random vibration input and a frequency range usually starting at 5 Hz and extending to as high as 250 Hz. GSFC uses a sine sweep vibration input and a frequency range usually starting at 5 Hz and extending only to the limits of the coupled loads analysis (typically 50 to 60 Hz). However, both JPL and GSFC use force limiting to realistically notch spacecraft resonances and response (acceleration) limiting as necessary to protect spacecraft structure and hardware from exceeding design strength capabilities. Despite GSFC and JPL differences in spacecraft level vibration test approaches, both have uncovered a significant number of spacecraft design and workmanship anomalies in vibration tests. This paper will give an overview of JPL and GSFC spacecraft vibration testing approaches and provide a detailed description of spacecraft anomalies revealed.

  15. External vibrations measurement of reactor components

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, S A [Nuclear Electric plc, Barnwood (United Kingdom); Sugden, J [Magnox Electric, Berkeley (United Kingdom)

    1997-12-31

    The paper outlines the use of External Vibration Monitoring for remote vibration assessment of internal reactor components. The main features of the technique are illustrated by a detailed examination of the specific application to the problem of Heysham 2 Fuel Plug Unit monitoring. (author). 6 figs.

  16. Vibration mode and vibration shape under excitation of a three phase model transformer core

    Science.gov (United States)

    Okabe, Seiji; Ishigaki, Yusuke; Omura, Takeshi

    2018-04-01

    Structural vibration characteristics and vibration shapes under three-phase excitation of a archetype transformer core were investigated to consider their influences on transformer noise. Acoustic noise and vibration behavior were measured in a three-limb model transformer core. Experimental modal analysis by impact test was performed. The vibration shapes were measured by a laser scanning vibrometer at different exciting frequencies. Vibration amplitude of the core in out-of-plane direction were relatively larger than those in other two in-plane directions. It was consistent with the result that the frequency response function of the core in out-of-plane direction was larger by about 20 dB or more than those in in-plane directions. There were many vibration modes having bending deformation of limbs in out-of-plane direction. The vibration shapes of the core when excited at 50 Hz and 60 Hz were almost the same because the fundamental frequencies of the vibration were not close to the resonance frequencies. When excitation frequency was 69 Hz which was half of one of the resonance frequencies, the vibration shape changed to the one similar to the resonance vibration mode. Existence of many vibration modes in out-of-plane direction of the core was presumed to be a reason why frequency characteristics of magnetostriction and transformer noise do not coincide.

  17. Optical fiber grating vibration sensor for vibration monitoring of hydraulic pump

    Science.gov (United States)

    Zhang, Zhengyi; Liu, Chuntong; Li, Hongcai; He, Zhenxin; Zhao, Xiaofeng

    2017-06-01

    In view of the existing electrical vibration monitoring traditional hydraulic pump vibration sensor, the high false alarm rate is susceptible to electromagnetic interference and is not easy to achieve long-term reliable monitoring, based on the design of a beam of the uniform strength structure of the fiber Bragg grating (FBG) vibration sensor. In this paper, based on the analysis of the vibration theory of the equal strength beam, the principle of FBG vibration tuning based on the equal intensity beam is derived. According to the practical application of the project, the structural dimensions of the equal strength beam are determined, and the optimization design of the vibrator is carried out. The finite element analysis of the sensor is carried out by ANSYS, and the first order resonant frequency is 94.739 Hz. The vibration test of the sensor is carried out by using the vibration frequency of 35 Hz and the vibration source of 50 Hz. The time domain and frequency domain analysis results of test data show that the sensor has good dynamic response characteristics, which can realize the accurate monitoring of the vibration frequency and meet the special requirements of vibration monitoring of hydraulic pump under specific environment.

  18. Ultra-low-vibration pulse-tube cryocooler system - cooling capacity and vibration

    Science.gov (United States)

    Ikushima, Yuki; Li, Rui; Tomaru, Takayuki; Sato, Nobuaki; Suzuki, Toshikazu; Haruyama, Tomiyoshi; Shintomi, Takakazu; Yamamoto, Akira

    2008-09-01

    This report describes the development of low-vibration cooling systems with pulse-tube (PT) cryocoolers. Generally, PT cryocoolers have the advantage of lower vibrations in comparison to those of GM cryocoolers. However, cooling systems for the cryogenic laser interferometer observatory (CLIO), which is a gravitational wave detector, require an operational vibration that is sufficiently lower than that of a commercial PT cryocooler. The required specification for the vibration amplitude in cold stages is less than ±1 μm. Therefore, during the development of low-vibration cooling systems for the CLIO, we introduced advanced countermeasures for commercial PT cryocoolers. The cooling performance and the vibration amplitude were evaluated. The results revealed that 4 K and 80 K PT cooling systems with a vibration amplitude of less than ±1 μm and cooling performance of 4.5 K and 70 K at heat loads of 0.5 W and 50 W, respectively, were developed successfully.

  19. Phosphate vibrations as reporters of DNA hydration

    Science.gov (United States)

    Corcelli, Steven

    The asymmetric phosphate stretch vibrational frequency is extraordinarily sensitive to its local solvent environment. Using density functional theory calculations on the model compound dimethyl phosphate, the asymmetric phosphate stretch vibrational frequency was found to shift linearly with the magnitude of an electric field along the symmetry axis of the PO2 moiety (i.e. the asymmetric phosphate stretch is an excellent linear vibrational Stark effect probe). With this linear relationship established, asymmetric phosphate stretch vibrational frequencies were computed during the course of a molecular dynamics simulation of fully hydrated DNA. Moreover, contributions to shifts in the frequencies from subpopulations of water molecules (e.g. backbone, minor groove, major groove, etc.) were calculated to reveal how phosphate vibrations report the onset of DNA hydration in experiments that vary the relative humidity of non-condensing (dry) DNA samples.

  20. High Energy Vibration for Gas Piping

    Science.gov (United States)

    Lee, Gary Y. H.; Chan, K. B.; Lee, Aylwin Y. S.; Jia, ShengXiang

    2017-07-01

    In September 2016, a gas compressor in offshore Sarawak has its rotor changed out. Prior to this change-out, pipe vibration study was carried-out by the project team to evaluate any potential high energy pipe vibration problems at the compressor’s existing relief valve downstream pipes due to process condition changes after rotor change out. This paper covers high frequency acoustic excitation (HFAE) vibration also known as acoustic induced vibration (AIV) study and discusses detailed methodologies as a companion to the Energy Institute Guidelines for the avoidance of vibration induced fatigue failure, which is a common industry practice to assess and mitigate for AIV induced fatigue failure. Such detailed theoretical studies can help to minimize or totally avoid physical pipe modification, leading to reduce offshore plant shutdown days to plant shutdowns only being required to accommodate gas compressor upgrades, reducing cost without compromising process safety.

  1. Mechanism of bubble detachment from vibrating walls

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dongjun; Park, Jun Kwon, E-mail: junkeun@postech.ac.kr; Kang, Kwan Hyoung [Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), San 31, Hyoja-dong, Pohang 790-784 (Korea, Republic of); Kang, In Seok [Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), San 31, Hyoja-dong, Pohang 790-784 (Korea, Republic of)

    2013-11-15

    We discovered a previously unobserved mechanism by which air bubbles detach from vibrating walls in glasses containing water. Chaotic oscillation and subsequent water jets appeared when a wall vibrated at greater than a critical level. Wave forms were developed at water-air interface of the bubble by the wall vibration, and water jets were formed when sufficiently grown wave-curvatures were collapsing. Droplets were pinched off from the tip of jets and fell to the surface of the glass. When the solid-air interface at the bubble-wall attachment point was completely covered with water, the bubble detached from the wall. The water jets were mainly generated by subharmonic waves and were generated most vigorously when the wall vibrated at the volume resonant frequency of the bubble. Bubbles of specific size can be removed by adjusting the frequency of the wall's vibration.

  2. Systematic vibration thermodynamic properties of bromine

    Science.gov (United States)

    Liu, G. Y.; Sun, W. G.; Liao, B. T.

    2015-11-01

    Based on the analysis of the maturity and finiteness of vibrational levels of bromine molecule in ground state and evaluating the effect on statistical computation, according to the elementary principles of quantum statistical theorem, using the full set of bromine molecular vibrational levels determined with algebra method, the statistical contribution for bromine systematical macroscopic thermodynamic properties is discussed. Thermodynamic state functions Helmholtz free energy, entropy and observable vibration heat capacity are calculated. The results show that the determination of full set of vibrational levels and maximum vibrational quantum number is the key in the correct statistical analysis of bromine systematical thermodynamic property. Algebra method results are clearly different from data of simple harmonic oscillator and the related algebra method results are no longer analytical but numerical and are superior to simple harmonic oscillator results. Compared with simple harmonic oscillator's heat capacities, the algebra method's heat capacities are more consistent with the experimental data in the given temperature range of 600-2100 K.

  3. Mediatized play

    DEFF Research Database (Denmark)

    Johansen, Stine Liv

    Children’s play must nowadays be understood as a mediatized field in society and culture. Media – understood in a very broad sense - holds severe explanatory power in describing and understanding the practice of play, since play happens both with, through and inspired by media of different sorts........ In this presentation the case of ‘playing soccer’ will be outlined through its different mediated manifestations, including soccer games and programs on TV, computer games, magazines, books, YouTube videos and soccer trading cards....

  4. Mediating Business

    DEFF Research Database (Denmark)

    "Mediating Business" is a study of the expansion of business journalism. Building on evidence from Denmark, Finland, Norway and Sweden, "Mediating Business" is a comparative and multidisciplinary study of one of the major transformations of the mass media and the realm of business - nationally...... and globally. The book explores the history of key innovations and innovators in the business press. It analyzes changes in the discourse of business journalism associated with the growth in business news and the development of new ways of framing business issues and events. Finally, it examines...... the organizational implications of the increased media visibility of business and, in particular, the development of corporate governance and media relations....

  5. Vibrational lifetimes of protein amide modes

    International Nuclear Information System (INIS)

    Peterson, K.A.; Rella, C.A.

    1995-01-01

    Measurement of the lifetimes of vibrational modes in proteins has been achieved with a single frequency infrared pump-probe technique using the Stanford Picosecond Free-electron Laser, These are the first direct measurements of vibrational dynamics in the polyamide structure of proteins. In this study, modes associated with the protein backbone are investigated. Results for the amide I band, which consists mainly of the stretching motion of the carbonyl unit of the amide linkage, show that relaxation from the first vibrational excited level (v=1) to the vibrational ground state (v=0) occurs within 1.5 picoseconds with apparent first order kinetics. Comparison of lifetimes for myoglobin and azurin, which have differing secondary structures, show a small but significant difference. The lifetime for the amide I band of myoglobin is 300 femtoseconds shorter than for azurin. Further measurements are in progress on other backbone vibrational modes and on the temperature dependence of the lifetimes. Comparison of vibrational dynamics for proteins with differing secondary structure and for different vibrational modes within a protein will lead to a greater understanding of energy transfer and dissipation in biological systems. In addition, these results have relevance to tissue ablation studies which have been conducted with pulsed infrared lasers. Vibrational lifetimes are necessary for calculating the rate at which the energy from absorbed infrared photons is converted to equilibrium thermal energy within the irradiated volume. The very fast vibrational lifetimes measured here indicate that mechanisms which involve direct vibrational up-pumping of the amide modes with consecutive laser pulses, leading to bond breakage or weakening, are not valid

  6. Energy scavenging from environmental vibration.

    Energy Technology Data Exchange (ETDEWEB)

    Galchev, Tzeno (University of Michigan); Apblett, Christopher Alan; Najafi, Khalil (University of Michigan)

    2009-10-01

    The goal of this project is to develop an efficient energy scavenger for converting ambient low-frequency vibrations into electrical power. In order to achieve this a novel inertial micro power generator architecture has been developed that utilizes the bi-stable motion of a mechanical mass to convert a broad range of low-frequency (< 30Hz), and large-deflection (>250 {micro}m) ambient vibrations into high-frequency electrical output energy. The generator incorporates a bi-stable mechanical structure to initiate high-frequency mechanical oscillations in an electromagnetic scavenger. This frequency up-conversion technique enhances the electromechanical coupling and increases the generated power. This architecture is called the Parametric Frequency Increased Generator (PFIG). Three generations of the device have been fabricated. It was first demonstrated using a larger bench-top prototype that had a functional volume of 3.7cm3. It generated a peak power of 558{micro}W and an average power of 39.5{micro}W at an input acceleration of 1g applied at 10 Hz. The performance of this device has still not been matched by any other reported work. It yielded the best power density and efficiency for any scavenger operating from low-frequency (<10Hz) vibrations. A second-generation device was then fabricated. It generated a peak power of 288{micro}W and an average power of 5.8{micro}W from an input acceleration of 9.8m/s{sup 2} at 10Hz. The device operates over a frequency range of 20Hz. The internal volume of the generator is 2.1cm{sup 3} (3.7cm{sup 3} including casing), half of a standard AA battery. Lastly, a piezoelectric version of the PFIG is currently being developed. This device clearly demonstrates one of the key features of the PFIG architecture, namely that it is suitable for MEMS integration, more so than resonant generators, by incorporating a brittle bulk piezoelectric ceramic. This is the first micro-scale piezoelectric generator capable of <10Hz operation. The

  7. Long-Range Vibrational Dynamics Are Directed by Watson-Crick Base Pairing in Duplex DNA.

    Science.gov (United States)

    Hithell, Gordon; Shaw, Daniel J; Donaldson, Paul M; Greetham, Gregory M; Towrie, Michael; Burley, Glenn A; Parker, Anthony W; Hunt, Neil T

    2016-05-05

    Ultrafast two-dimensional infrared (2D-IR) spectroscopy of a 15-mer A-T DNA duplex in solution has revealed structure-dependent vibrational coupling and energy transfer processes linking bases with the sugar-phosphate backbone. Duplex melting induces significant changes in the positions of off-diagonal peaks linking carbonyl and ring-stretching vibrational modes of the adenine and thymine bases with vibrations of the phosphate group and phosphodiester linkage. These indicate that Watson-Crick hydrogen bonding and helix formation lead to a unique vibrational coupling arrangement of base vibrational modes with those of the phosphate unit. On the basis of observations from time-resolved 2D-IR data, we conclude that rapid energy transfer processes occur between base and backbone, mediated by additional modes located on the deoxyribose moiety within the same nucleotide. These relaxation dynamics are insensitive to duplex melting, showing that efficient intramolecular energy relaxation to the solvent via the phosphate groups is the key to excess energy dissipation in both single- and double-stranded DNA.

  8. Vibration converter with magnetic levitation

    Science.gov (United States)

    Gladilin, A. V.; Pirogov, V. A.; Golyamina, I. P.; Kulaev, U. V.; Kurbatov, P. A.; Kurbatova, E. P.

    2015-05-01

    The paper presents a mathematical model, the results of computational and theoretical research, and the feasibility of creating a vibration converter with full magnetic levitation in the suspension of a high-temperature superconductor (HTSC). The axial and radial stability of the active part of the converter is provided by the interaction of the magnetic field of ring-shaped permanent magnets and a hollow cylinder made of the ceramic HTSC material. The force is created by a system of current-carrying coils whose magnetic field is polarized by permanent magnets and interacts with induced currents in the superconducting cylinder. The case of transition to the superconducting state of HTSC material in the field of the permanent magnets (FC mode) is considered. The data confirm the outlook for the proposed technical solutions.

  9. Granular metamaterials for vibration mitigation

    Science.gov (United States)

    Gantzounis, G.; Serra-Garcia, M.; Homma, K.; Mendoza, J. M.; Daraio, C.

    2013-09-01

    Acoustic metamaterials that allow low-frequency band gaps are interesting for many practical engineering applications, where vibration control and sound insulation are necessary. In most prior studies, the mechanical response of these structures has been described using linear continuum approximations. In this work, we experimentally and theoretically address the formation of low-frequency band gaps in locally resonant granular crystals, where the dynamics of the system is governed by discrete equations. We investigate the quasi-linear behavior of such structures. The analysis shows that a stopband can be introduced at about one octave lower frequency than in materials without local resonances. Broadband and multi-frequency stopband characteristics can also be achieved by strategically tailoring the non-uniform local resonance parameters.

  10. Carbon Nanotube Tape Vibrating Gyroscope

    Science.gov (United States)

    Tucker, Dennis Stephen (Inventor)

    2016-01-01

    A vibrating gyroscope includes a piezoelectric strip having length and width dimensions. The piezoelectric strip includes a piezoelectric material and carbon nanotubes (CNTs) substantially aligned and polled along the strip's length dimension. A spindle having an axis of rotation is coupled to the piezoelectric strip. The axis of rotation is parallel to the strip's width dimension. A first capacitance sensor is mechanically coupled to the spindle for rotation therewith. The first capacitance sensor is positioned at one of the strip's opposing ends and is spaced apart from one of the strip's opposing faces. A second capacitance sensor is mechanically coupled to the spindle for rotation therewith. The second capacitance sensor is positioned at another of the strip's opposing ends and is spaced apart from another of the strip's opposing faces. A voltage source applies an AC voltage to the piezoelectric strip.

  11. Super-multiplex vibrational imaging

    Science.gov (United States)

    Wei, Lu; Chen, Zhixing; Shi, Lixue; Long, Rong; Anzalone, Andrew V.; Zhang, Luyuan; Hu, Fanghao; Yuste, Rafael; Cornish, Virginia W.; Min, Wei

    2017-04-01

    The ability to visualize directly a large number of distinct molecular species inside cells is increasingly essential for understanding complex systems and processes. Even though existing methods have successfully been used to explore structure-function relationships in nervous systems, to profile RNA in situ, to reveal the heterogeneity of tumour microenvironments and to study dynamic macromolecular assembly, it remains challenging to image many species with high selectivity and sensitivity under biological conditions. For instance, fluorescence microscopy faces a ‘colour barrier’, owing to the intrinsically broad (about 1,500 inverse centimetres) and featureless nature of fluorescence spectra that limits the number of resolvable colours to two to five (or seven to nine if using complicated instrumentation and analysis). Spontaneous Raman microscopy probes vibrational transitions with much narrower resonances (peak width of about 10 inverse centimetres) and so does not suffer from this problem, but weak signals make many bio-imaging applications impossible. Although surface-enhanced Raman scattering offers high sensitivity and multiplicity, it cannot be readily used to image specific molecular targets quantitatively inside live cells. Here we use stimulated Raman scattering under electronic pre-resonance conditions to image target molecules inside living cells with very high vibrational selectivity and sensitivity (down to 250 nanomolar with a time constant of 1 millisecond). We create a palette of triple-bond-conjugated near-infrared dyes that each displays a single peak in the cell-silent Raman spectral window; when combined with available fluorescent probes, this palette provides 24 resolvable colours, with the potential for further expansion. Proof-of-principle experiments on neuronal co-cultures and brain tissues reveal cell-type-dependent heterogeneities in DNA and protein metabolism under physiological and pathological conditions, underscoring the

  12. Evaluation of vibration and vibration fatigue life for small bore pipe in nuclear power plants

    International Nuclear Information System (INIS)

    Wang Zhaoxi; Xue Fei; Gong Mingxiang; Ti Wenxin; Lin Lei; Liu Peng

    2011-01-01

    The assessment method of the steady state vibration and vibration fatigue life of the small bore pipe in the supporting system of the nuclear power plants is proposed according to the ASME-OM3 and EDF evaluation methods. The GGR supporting pipe system vibration is evaluated with this method. The evaluation process includes the filtration of inborn sensitivity, visual inspection, vibration tests, allowable vibration effective velocity calculation and vibration stress calculation. With the allowable vibration effective velocity calculated and the vibration velocity calculated according to the acceleration data tested, the filtrations are performed. The vibration stress at the welding coat is calculated with the spectrum method and compared with the allowable value. The response of the stress is calculated with the transient dynamic method, with which the fatigue life is evaluated with the Miners linear accumulation model. The vibration stress calculated with the spectrum method exceeds the allowable value, while the fatigue life calculated from the transient dynamic method is larger than the designed life with a big safety margin. (authors)

  13. Review of Energy Harvesters Utilizing Bridge Vibrations

    Directory of Open Access Journals (Sweden)

    Farid Ullah Khan

    2016-01-01

    Full Text Available For health monitoring of bridges, wireless acceleration sensor nodes (WASNs are normally used. In bridge environment, several forms of energy are available for operating WASNs that include wind, solar, acoustic, and vibration energy. However, only bridge vibration has the tendency to be utilized for embedded WASNs application in bridge structures. This paper reports on the recent advancements in the area of vibration energy harvesters (VEHs utilizing bridge oscillations. The bridge vibration is narrowband (1 to 40 Hz with low acceleration levels (0.01 to 3.8 g. For utilization of bridge vibration, electromagnetic based vibration energy harvesters (EM-VEHs and piezoelectric based vibration energy harvesters (PE-VEHs have been developed. The power generation of the reported EM-VEHs is in the range from 0.7 to 1450000 μW. However, the power production by the developed PE-VEHs ranges from 0.6 to 7700 μW. The overall size of most of the bridge VEHs is quite comparable and is in mesoscale. The resonant frequencies of EM-VEHs are on the lower side (0.13 to 27 Hz in comparison to PE-VEHs (1 to 120 Hz. The power densities reported for these bridge VEHs range from 0.01 to 9539.5 μW/cm3 and are quite enough to operate most of the commercial WASNs.

  14. Bevel Gearbox Fault Diagnosis using Vibration Measurements

    Directory of Open Access Journals (Sweden)

    Hartono Dennis

    2016-01-01

    Full Text Available The use of vibration measurementanalysis has been proven to be effective for gearbox fault diagnosis. However, the complexity of vibration signals observed from a gearbox makes it difficult to accurately detectfaults in the gearbox. This work is based on a comparative studyof several time-frequency signal processing methods that can be used to extract information from transient vibration signals containing useful diagnostic information. Experiments were performed on a bevel gearbox test rig using vibration measurements obtained from accelerometers. Initially, thediscrete wavelet transform was implementedfor vibration signal analysis to extract the frequency content of signal from the relevant frequency region. Several time-frequency signal processing methods werethen incorporated to extract the fault features of vibration signals and their diagnostic performances were compared. It was shown thatthe Short Time Fourier Transform (STFT could not offer a good time resolution to detect the periodicity of the faulty gear tooth due the difficulty in choosing an appropriate window length to capture the impulse signal. The Continuous Wavelet Transform (CWT, on the other hand, was suitable to detection of vibration transients generated by localized fault from a gearbox due to its multi-scale property. However, both methods still require a thorough visual inspection. In contrast, it was shown from the experiments that the diagnostic method using the Cepstrumanalysis could provide a direct indication of the faulty tooth without the need of a thorough visual inspection as required by CWT and STFT.

  15. Investigation of vibration characteristics of electric motors

    Science.gov (United States)

    Bakshis, A. K.; Tamoshyunas, Y. K.

    1973-01-01

    The vibration characteristics of electric motors were analyzed using mathematical statistics methods. The equipment used and the method of conducting the test are described. Curves are developed to show the visualization of the electric motor vibrations in the vertical direction. Additional curves are included to show the amplitude-phase frequency characteristic of dynamic rotor-housing vibrations at the first lug and the same data for the second lug of the electric motor. Mathematical models were created to show the transmission function of the dynamic rotor housing system.

  16. Controlling flexible rotor vibrations using parametric excitation

    Energy Technology Data Exchange (ETDEWEB)

    Atepor, L, E-mail: katepor@yahoo.co [Department of Mechanical Engineering, University of Glasgow, G12 8QQ (United Kingdom)

    2009-08-01

    This paper presents both theoretical and experimental studies of an active vibration controller for vibration in a flexible rotor system. The paper shows that the vibration amplitude can be modified by introducing an axial parametric excitation. The perturbation method of multiple scales is used to solve the equations of motion. The steady-state responses, with and without the parametric excitation terms, is investigated. An experimental test machine uses a piezoelectric exciter mounted on the end of the shaft. The results show a reduction in the rotor response amplitude under principal parametric resonance, and some good correlation between theory and experiment.

  17. Experimental chaos in nonlinear vibration isolation system

    International Nuclear Information System (INIS)

    Lou Jingjun; Zhu Shijian; He Lin; He Qiwei

    2009-01-01

    The chaotic vibration isolation method was studied thoroughly from an experimental perspective. The nonlinear load-deflection characteristic of the conical coil spring used in the experiment was surveyed. Chaos and subharmonic responses including period-2 and period-6 motions were observed. The line spectrum reduction and the drop of the acceleration vibration level in chaotic state and that in non-chaotic state were compared, respectively. It was concluded from the experiment that the nonlinear vibration isolation system in chaotic state has strong ability in line spectrum reduction.

  18. Vibration behavior optimization of planetary gear sets

    Directory of Open Access Journals (Sweden)

    Farshad Shakeri Aski

    2014-12-01

    Full Text Available This paper presents a global optimization method focused on planetary gear vibration reduction by means of tip relief profile modifications. A nonlinear dynamic model is used to study the vibration behavior. In order to investigate the optimal radius and amplitude, Brute Force method optimization is used. One approach in optimization is straightforward and requires considerable computation power: brute force methods try to calculate all possible solutions and decide afterwards which one is the best. Results show the influence of optimal profile on planetary gear vibrations.

  19. Review of magnetostrictive vibration energy harvesters

    Science.gov (United States)

    Deng, Zhangxian; Dapino, Marcelo J.

    2017-10-01

    The field of energy harvesting has grown concurrently with the rapid development of portable and wireless electronics in which reliable and long-lasting power sources are required. Electrochemical batteries have a limited lifespan and require periodic recharging. In contrast, vibration energy harvesters can supply uninterrupted power by scavenging useful electrical energy from ambient structural vibrations. This article reviews the current state of vibration energy harvesters based on magnetostrictive materials, especially Terfenol-D and Galfenol. Existing magnetostrictive harvester designs are compared in terms of various performance metrics. Advanced techniques that can reduce device size and improve performance are presented. Models for magnetostrictive devices are summarized to guide future harvester designs.

  20. Vibration-Induced Climbing of Drops

    Science.gov (United States)

    Brunet, P.; Eggers, J.; Deegan, R. D.

    2007-10-01

    We report an experimental study of liquid drops moving against gravity, when placed on a vertically vibrating inclined plate, which is partially wetted by the drop. The frequency of vibrations ranges from 30 to 200 Hz, and, above a threshold in vibration acceleration, drops experience an upward motion. We attribute this surprising motion to the deformations of the drop, as a consequence of an up or down symmetry breaking induced by the presence of the substrate. We relate the direction of motion to contact angle measurements. This phenomenon can be used to move a drop along an arbitrary path in a plane, without special surface treatments or localized forcing.

  1. Vibrational and Thermal Properties of Oxyanionic Crystals

    Science.gov (United States)

    Korabel'nikov, D. V.

    2018-03-01

    The vibrational and thermal properties of dolomite and alkali chlorates and perchlorates were studied in the gradient approximation of density functional theory using the method of a linear combination of atomic orbitals (LCAO). Long-wave vibration frequencies, IR and Raman spectra, and mode Gruneisen parameters were calculated. Equation-of-state parameters, thermodynamic potentials, entropy, heat capacity, and thermal expansion coefficient were also determined. The thermal expansion coefficient of dolomite was established to be much lower than for chlorates and perchlorates. The temperature dependence of the heat capacity at T > 200 K was shown to be generally governed by intramolecular vibrations.

  2. Vibration Measurement with PULSE and DSPACE Equipment

    Directory of Open Access Journals (Sweden)

    Radim KLEČKA

    2009-06-01

    Full Text Available This contribution describes techniques and results of measurement with TIRA vibration generator. A method of experimental modal analysis allows next restore of vibration data. The goal is check validity of head expanders and screw connection. This process is based to using ME’scope environment. Another goal is check possibilities of dSPACE platform to vibration measurement. This task includes design of connection between dSPACE system and power amplifier, creating of graphical user interface and analyzing main configuration parameters to improve quality of drive signal.

  3. Model Predictive Vibration Control Efficient Constrained MPC Vibration Control for Lightly Damped Mechanical Structures

    CERN Document Server

    Takács, Gergely

    2012-01-01

    Real-time model predictive controller (MPC) implementation in active vibration control (AVC) is often rendered difficult by fast sampling speeds and extensive actuator-deformation asymmetry. If the control of lightly damped mechanical structures is assumed, the region of attraction containing the set of allowable initial conditions requires a large prediction horizon, making the already computationally demanding on-line process even more complex. Model Predictive Vibration Control provides insight into the predictive control of lightly damped vibrating structures by exploring computationally efficient algorithms which are capable of low frequency vibration control with guaranteed stability and constraint feasibility. In addition to a theoretical primer on active vibration damping and model predictive control, Model Predictive Vibration Control provides a guide through the necessary steps in understanding the founding ideas of predictive control applied in AVC such as: ·         the implementation of ...

  4. On the neutron noise diagnostics of pressurized water reactor control rod vibrations II. Stochastic vibrations

    International Nuclear Information System (INIS)

    Pazsit, I.; Glockler, O.

    1984-01-01

    In an earlier publication, using the theory of neutron fluctuations induced by a vibrating control rod, a complete formal solution of rod vibration diagnostics based on neutron noise measurements was given in terms of Fourier-transformed neutron detector time signals. The suggested procedure was checked in numerical simulation tests where only periodic vibrations could be considered. The procedure and its numerical testing are elaborated for stochastic two-dimensional vibrations. A simple stochastic theory of two-dimensional flow-induced vibrations is given; then the diagnostic method is formulated in the stochastic case, that is, in terms of neutron detector auto- and crosspower spectra. A previously suggested approximate rod localization technique is also formulated in the stochastic case. Applicability of the methods is then investigated in numerical simulation tests, using the proposed model of stochastic two-dimensional vibrations when generating neutron detector spectra that simulate measured data

  5. Current-induced runaway vibrations in dehydrogenated graphene nanoribbons

    Directory of Open Access Journals (Sweden)

    Rasmus Bjerregaard Christensen

    2016-01-01

    Full Text Available We employ a semi-classical Langevin approach to study current-induced atomic dynamics in a partially dehydrogenated armchair graphene nanoribbon. All parameters are obtained from density functional theory. The dehydrogenated carbon dimers behave as effective impurities, whose motion decouples from the rest of carbon atoms. The electrical current can couple the dimer motion in a coherent fashion. The coupling, which is mediated by nonconservative and pseudo-magnetic current-induced forces, change the atomic dynamics, and thereby show their signature in this simple system. We study the atomic dynamics and current-induced vibrational instabilities using a simplified eigen-mode analysis. Our study illustrates how armchair nanoribbons can serve as a possible testbed for probing the current-induced forces.

  6. The immediate effect of vibration therapy on flexibility in female ...

    African Journals Online (AJOL)

    The immediate effect of vibration therapy on flexibility in female junior elite gymnasts. ... Therefore, the aim of this study was to investigate the acute effects of vibration therapy on the flexibility of female gymnasts. A pre-test ... Keywords: Static stretching, vibration training, vibration therapy, acute effect, artistic gymnastics.

  7. Putting a damper on drilling's bad vibrations

    Energy Technology Data Exchange (ETDEWEB)

    Jardine, S. (Sedco forex, Montrouge (France)); Malone, D. (Anadrill, Sugar Land, TX (United States)); Sheppard, M. (Schlumberger Cambridge Research, Cambridge (United Kingdom))

    1994-01-01

    Harmful drilling vibrations are costing the industry dearly. Three main vibration types (axial, torsional and transverse) are explained and its causes discussed. Technology exists to eliminate most vibrations, but requires more systematic deployment than is usual. Hardware that eliminates vibrations is reviewed, including downhole shock measurement, torque feedback shock guards and antiwhirl bits. 9 figs., 11 refs.

  8. International Conference on Acoustics and Vibration

    CERN Document Server

    Chaari, Fakher; Walha, Lasaad; Abdennadher, Moez; Abbes, Mohamed; Haddar, Mohamed

    2017-01-01

    The book provides readers with a snapshot of recent research and industrial trends in field of industrial acoustics and vibration. Each chapter, accepted after a rigorous peer-review process, reports on a selected, original piece of work presented and discussed at International Conference on Acoustics and Vibration (ICAV2016), which was organized by the Tunisian Association of Industrial Acoustics and Vibration (ATAVI) and held March 21-23, in Hammamet, Tunisia. The contributions, mainly written by north African authors, covers advances in both theory and practice in a variety of subfields, such as: smart materials and structures; fluid-structure interaction; structural acoustics as well as computational vibro-acoustics and numerical methods. Further topics include: engines control, noise identification, robust design, flow-induced vibration and many others.This book provides a valuable resource for both academics and professionals dealing with diverse issues in applied mechanics. By combining advanced theori...

  9. whole body vibration and spinal stabilisation

    African Journals Online (AJOL)

    A range of exercise modalities is used in the rehabilitation of indi- viduals with chronic lower ... effects of whole body vibration (WBV) therapy and conventional ... with musculoskeletal, sensory, emotional, cognitive and behavioural components ...

  10. Piezoelectric energy harvesting from broadband random vibrations

    International Nuclear Information System (INIS)

    Adhikari, S; Friswell, M I; Inman, D J

    2009-01-01

    Energy harvesting for the purpose of powering low power electronic sensor systems has received explosive attention in the last few years. Most works using deterministic approaches focusing on using the piezoelectric effect to harvest ambient vibration energy have concentrated on cantilever beams at resonance using harmonic excitation. Here, using a stochastic approach, we focus on using a stack configuration and harvesting broadband vibration energy, a more practically available ambient source. It is assumed that the ambient base excitation is stationary Gaussian white noise, which has a constant power-spectral density across the frequency range considered. The mean power acquired from a piezoelectric vibration-based energy harvester subjected to random base excitation is derived using the theory of random vibrations. Two cases, namely the harvesting circuit with and without an inductor, have been considered. Exact closed-form expressions involving non-dimensional parameters of the electromechanical system have been given and illustrated using numerical examples

  11. Piezoelectric energy harvesting from broadband random vibrations

    Science.gov (United States)

    Adhikari, S.; Friswell, M. I.; Inman, D. J.

    2009-11-01

    Energy harvesting for the purpose of powering low power electronic sensor systems has received explosive attention in the last few years. Most works using deterministic approaches focusing on using the piezoelectric effect to harvest ambient vibration energy have concentrated on cantilever beams at resonance using harmonic excitation. Here, using a stochastic approach, we focus on using a stack configuration and harvesting broadband vibration energy, a more practically available ambient source. It is assumed that the ambient base excitation is stationary Gaussian white noise, which has a constant power-spectral density across the frequency range considered. The mean power acquired from a piezoelectric vibration-based energy harvester subjected to random base excitation is derived using the theory of random vibrations. Two cases, namely the harvesting circuit with and without an inductor, have been considered. Exact closed-form expressions involving non-dimensional parameters of the electromechanical system have been given and illustrated using numerical examples.

  12. Vibrational anomalies and marginal stability of glasses

    KAUST Repository

    Marruzzo, Alessia; Kö hler, Stephan; Fratalocchi, Andrea; Ruocco, Giancarlo; Schirmacher, Walter

    2013-01-01

    The experimentally measured vibrational spectrum of glasses strongly deviates from that expected in Debye's elasticity theory: The density of states deviates from Debye's ω2 law ("boson peak"), the sound velocity shows a negative dispersion

  13. Adaptive vibration isolation system for diesel engine

    Institute of Scientific and Technical Information of China (English)

    YANG Tie-jun; ZHANG Xin-yu; XIAO You-hong; HUANG Jin-e; LIU Zhi-gang

    2004-01-01

    An active two-stage isolation mounting, on which servo-hydraulic system is used as the actuator (secondary vibration source) and a diesel engine is used as primary vibration source, has been built. The upper mass of the mounting is composed of a 495diesel and an electrical eddy current dynamometer. The lower mass is divided into four small masses to which servo-hydraulic actuator and rubber isolators are attached. According to the periodical characteristics of diesel vibration signals, a multi-point adaptive strategy based on adaptive comb filtered algorithm is applied to active multi-direction coupled vibrations control for the engine. The experimental results demonstrate that a good suppression in the effective range of phase compensation in secondary path (within 100Hz) at different operation conditions is achieved, and verify that this strategy is effective. The features of the active system, the development activities carried out on the system and experimental results are discussed in the paper.

  14. Vibrational and electronic spectroscopic studies of melatonin

    Science.gov (United States)

    Singh, Gurpreet; Abbas, J. M.; Dogra, Sukh Dev; Sachdeva, Ritika; Rai, Bimal; Tripathi, S. K.; Prakash, Satya; Sathe, Vasant; Saini, G. S. S.

    2014-01-01

    We report the infrared absorption and Raman spectra of melatonin recorded with 488 and 632.8 nm excitations in 3600-2700 and 1700-70 cm-1 regions. Further, we optimized molecular structure of the three conformers of melatonin within density functional theory calculations. Vibrational frequencies of all three conformers have also been calculated. Observed vibrational bands have been assigned to different vibrational motions of the molecules on the basis of potential energy distribution calculations and calculated vibrational frequencies. Observed band positions match well with the calculated values after scaling except Nsbnd H stretching mode frequencies. It is found that the observed and calculated frequencies mismatch of Nsbnd H stretching is due to intermolecular interactions between melatonin molecules.

  15. Analytic vibrational matrix elements for diatomic molecules

    International Nuclear Information System (INIS)

    Bouanich, J.P.; Ogilvie, J.F.; Tipping, R.H.

    1986-01-01

    The vibrational matrix elements and expectation values for a diatomic molecule, including the rotational dependence, are calculated for powers of the reduced displacement in terms of the parameters of the Dunham potential-energy function. (orig.)

  16. Magnetically levitated autoparametric broadband vibration energy harvesting

    International Nuclear Information System (INIS)

    Kurmann, L.; Jia, Y.; Manoli, Y.; Woias, P.

    2016-01-01

    Some of the lingering challenges within the current paradigm of vibration energy harvesting (VEH) involve narrow operational frequency range and the inevitable non-resonant response from broadband noise excitations. Such VEHs are only suitable for limited applications with fixed sinusoidal vibration, and fail to capture a large spectrum of the real world vibration. Various arraying designs, frequency tuning schemes and nonlinear vibratory approaches have only yielded modest enhancements. To fundamentally address this, the paper proposes and explores the potentials in using highly nonlinear magnetic spring force to activate an autoparametric oscillator, in order to realize an inherently broadband resonant system. Analytical and numerical modelling illustrate that high spring nonlinearity derived from magnetic levitation helps to promote the 2:1 internal frequency matching required to activate parametric resonance. At the right internal parameters, the resulting system can intrinsically exhibit semi-resonant response regardless of the bandwidth of the input vibration, including broadband white noise excitation. (paper)

  17. A Miniature Coupled Bistable Vibration Energy Harvester

    International Nuclear Information System (INIS)

    Zhu, D; Arthur, D C; Beeby, S P

    2014-01-01

    This paper reports the design and test of a miniature coupled bistable vibration energy harvester. Operation of a bistable structure largely depends on vibration amplitude rather than frequency, which makes it very promising for wideband vibration energy harvesting applications. A coupled bistable structure consists of a pair of mobile magnets that create two potential wells and thus the bistable phenomenon. It requires lower excitation to trigger bistable operation compared to conventional bistable structures. Based on previous research, this work focused on miniaturisation of the coupled bistable structure for energy harvesting application. The proposed bistable energy harvester is a combination of a Duffing's nonlinear structure and a linear assisting resonator. Experimental results show that the output spectrum of the miniature coupled bistable vibration energy harvester was the superposition of several spectra. It had a higher maximum output power and a much greater bandwidth compared to simply the Duffing's structure without the assisting resonator

  18. Vibrations and stability of complex beam systems

    CERN Document Server

    Stojanović, Vladimir

    2015-01-01

     This book reports on solved problems concerning vibrations and stability of complex beam systems. The complexity of a system is considered from two points of view: the complexity originating from the nature of the structure, in the case of two or more elastically connected beams; and the complexity derived from the dynamic behavior of the system, in the case of a damaged single beam, resulting from the harm done to its simple structure. Furthermore, the book describes the analytical derivation of equations of two or more elastically connected beams, using four different theories (Euler, Rayleigh, Timoshenko and Reddy-Bickford). It also reports on a new, improved p-version of the finite element method for geometrically nonlinear vibrations. The new method provides more accurate approximations of solutions, while also allowing us to analyze geometrically nonlinear vibrations. The book describes the appearance of longitudinal vibrations of damaged clamped-clamped beams as a result of discontinuity (damage). It...

  19. Vibrational and Rotational Energy Relaxation in Liquids

    DEFF Research Database (Denmark)

    Petersen, Jakob

    Vibrational and rotational energy relaxation in liquids are studied by means of computer simulations. As a precursor for studying vibrational energy relaxation of a solute molecule subsequent to the formation of a chemical bond, the validity of the classical Bersohn-Zewail model for describing......, the vibrational energy relaxation of I2 subsequent to photodissociation and recombination in CCl4 is studied using classical Molecular Dynamics simulations. The vibrational relaxation times and the time-dependent I-I pair distribution function are compared to new experimental results, and a qualitative agreement...... is found in both cases. Furthermore, the rotational energy relaxation of H2O in liquid water is studied via simulations and a power-and-work analysis. The mechanism of the energy transfer from the rotationally excited H2O molecule to its water neighbors is elucidated, i.e. the energy-accepting degrees...

  20. Vibration analysis and vibration damage assessment in nuclear and process equipment

    International Nuclear Information System (INIS)

    Pettigrew, M.J.; Taylor, C.E.; Fisher, N.J.; Yetisir, M.; Smith, B.A.W.

    1997-01-01

    Component failures due to excessive flow-induced vibration are still affecting the performance and reliability of process and nuclear components. The purpose of this paper is to discuss flow-induced vibration analysis and vibration damage prediction. Vibration excitation mechanisms are described with particular emphasis on fluid elastic instability. The dynamic characteristics of process and power equipment are explained. The statistical nature of some parameters, in particular support conditions, is discussed. The prediction of fretting-wear damage is approached from several points-of-view. An energy approach to formulate fretting-wear damage is proposed. (author)

  1. On the neutron noise diagnostics of pressurized water reactor control rod vibrations. 1. periodic vibrations

    International Nuclear Information System (INIS)

    Pazsit, I.; Glockler, O.

    1983-01-01

    Based on the theory of neutron noise arising from the vibration of a localized absorber, the possibility of rod vibration diagnostics is investigated. It is found that noise source characteristics, namely rod position and vibration trajectory and spectra, can be unfolded from measured neutron noise signals. For the localization process, the first and more difficult part of the diagnostics, a procedure is suggested whose novelty is that it is applicable in case of arbitrary vibration trajectories. Applicability of the method is investigated in numerical experiments where effects of background noise are also accounted for

  2. Active and passive vibration control of structures

    CERN Document Server

    Spelsberg-Korspeter, Gottfried

    2014-01-01

    Active and Passive Vibration Control of Structures form an issue of very actual interest in many different fields of engineering, for example in the automotive and aerospace industry, in precision engineering (e.g. in large telescopes), and also in civil engineering. The papers in this volume bring together engineers of different background, and it fill gaps between structural mechanics, vibrations and modern control theory.  Also links between the different applications in structural control are shown.

  3. Using Euler buckling springs for vibration isolation

    CERN Document Server

    Winterflood, J; Blair, D G

    2002-01-01

    Difficulties in obtaining ideal vertical vibration isolation with mechanical springs are identified as being due to the mass of the elastic element which is in turn due to its energy storage requirement. A new technique to minimize this energy is presented - being an Euler column undergoing elastic buckling. The design of a high performance vertical vibration isolation stage based on this technique is presented together with its measured performance.

  4. Using Euler buckling springs for vibration isolation

    International Nuclear Information System (INIS)

    Winterflood, J; Barber, T; Blair, D G

    2002-01-01

    Difficulties in obtaining ideal vertical vibration isolation with mechanical springs are identified as being due to the mass of the elastic element which is in turn due to its energy storage requirement. A new technique to minimize this energy is presented - being an Euler column undergoing elastic buckling. The design of a high performance vertical vibration isolation stage based on this technique is presented together with its measured performance

  5. Space shuttle main engine vibration data base

    Science.gov (United States)

    Lewallen, Pat

    1986-01-01

    The Space Shuttle Main Engine Vibration Data Base is described. Included is a detailed description of the data base components, the data acquisition process, the more sophisticated software routines, and the future data acquisition methods. Several figures and plots are provided to illustrate the various output formats accessible to the user. The numerous vibration data recall and analysis capabilities available through automated data base techniques are revealed.

  6. Studies of interstellar vibrationally-excited molecules

    International Nuclear Information System (INIS)

    Ziurys, L.M.; Snell, R.L.; Erickson, N.R.

    1986-01-01

    Several molecules thus far have been detected in the ISM in vibrationally-excited states, including H 2 , SiO, HC 3 N, and CH 3 CN. In order for vibrational-excitation to occur, these species must be present in unusually hot and dense gas and/or where strong infrared radiation is present. In order to do a more thorough investigation of vibrational excitation in the interstellar medium (ISM), studies were done of several mm-wave transitions originating in excited vibrational modes of HCN, an abundant interstellar molecule. Vibrationally-excited HCN was recently detected toward Orion-KL and IRC+10216, using a 12 meter antenna. The J=3-2 rotational transitions were detected in the molecule's lowest vibrational state, the bending mode, which is split into two separate levels, due to l-type doubling. This bending mode lies 1025K above ground state, with an Einstein A coefficient of 3.6/s. The J=3-2 line mode of HCN, which lies 2050K above ground state, was also observed toward IRC+10216, and subsequently in Orion-KL. Further measurements of vibrationally-excited HCN were done using a 14 meter telescope, which include the observations of the (0,1,0) and (0,2,0) modes towards Orion-KL, via their J=3-2 transitions at 265-267 GHz. The spectrum of the J=3-2 line in Orion taken with the 14 meter telescope, is shown, along with a map, which indicates that emission from vibrationally-excited HCN arises from a region probably smaller than the 14 meter telescope's 20 arcsec beam

  7. Actual behaviour of a ball vibration absorber

    Czech Academy of Sciences Publication Activity Database

    Pirner, Miroš

    2002-01-01

    Roč. 90, č. 8 (2002), s. 987-1005 ISSN 0167-6105 R&D Projects: GA ČR(CZ) GV103/96/K034 Institutional support: RVO:68378297 Keywords : TV towers * wind-excited vibrations * vibration absorbers * pendulum absorber Subject RIV: JM - Building Engineering Impact factor: 0.513, year: 2002 http://www.sciencedirect.com/science/article/pii/S0167610502002155#

  8. Prediction of induced vibrations in stall

    Energy Technology Data Exchange (ETDEWEB)

    Thirstrup Petersen, J; Thomsen, K; Aagaard Madsen, H [Risoe National Lab., Wind Energy and Atmospheric Physics Dept., Roskilde (Denmark)

    1999-03-01

    The main results from recent research in stall induced vibrations are presented. The focus is on the edgewise blade vibrations, which during the last decade have turned out to be a potential threat against the stable operation of stall regulated wind turbines and a fact, which must be dealt with by the designer. The basic physical explanation for the phenomenon and examples of design precaution, which can be taken, are presented. (au)

  9. Mechanical vibration where do we stand?

    CERN Document Server

    Schneider, Wilhelm; Elishakoff, Isaac

    2007-01-01

    Written by the world’s leading researchers on various topics of linear, nonlinear, and stochastic mechanical vibrations, this work gives an authoritative overview of the classic yet still very modern subject of mechanical vibrations. It poses the question: What are the most important contributions made in the past decade The reader will be able to gain a critical and authoritative overview of the subject from various complementary perspectives.

  10. Local-mode vibrations of water

    Energy Technology Data Exchange (ETDEWEB)

    Lawton, R.T.; Child, M.S. (Oxford Univ. (UK). Dept. of Theoretical Chemistry)

    1981-05-11

    Quantum-mechanical eigenvalues for the stretching vibrations of H/sub 2/O on the Sorbie-Murrell potential surface are shown to contain a series of local-mode doublets, with splittings which vary as the energy increases from 100 cm/sup -1/ at v=1 to 0.001 cm/sup -1/ at v=8. Preliminary calculations indicate that this pattern is largely unaffected by inclusion of the bending vibrational mode.

  11. Local-mode vibrations of water

    Energy Technology Data Exchange (ETDEWEB)

    Lawton, R.T.; Child, M.S. (Oxford Univ. (UK). Dept. of Theoretical Chemistry)

    1981-05-11

    Quantum-mechanical eigenvalues for the stretching vibrations of H/sub 2/O on the Sorbie-Murrell potential surface are shown to contain a series of local-mode doublets, with splittings which vary as the energy increases from 100 cm/sup -1/ at theta=1 to 0.001 cm/sup -1/ at theta=8. Preliminary calculations indicate that this pattern is largely unaffected by inclusion of the bending vibrational mode.

  12. Local-mode vibrations of water

    International Nuclear Information System (INIS)

    Lawton, R.T.; Child, M.S.

    1981-01-01

    Quantum-mechanical eigenvalues for the stretching vibrations of H 2 O on the Sorbie-Murrell potential surface are shown to contain a series of local-mode doublets, with splittings which vary as the energy increases from 100 cm - 1 at v=1 to 0.001 cm - 1 at v=8. Preliminary calculations indicate that this pattern is largely unaffected by inclusion of the bending vibrational mode. (author)

  13. Optical vibration measurement of mechatronics devices

    Science.gov (United States)

    Yanabe, Shigeo

    1993-09-01

    An optical vibration measuring system which enables to detect both linear and angular displacement of 25 nm and 5 prad was developed. The system is mainly composed of a He-Ne laser, a displacement detecting photo-diode and lenses, and has linear and angular displacement magnification mechanism using two different principles of optical lever. The system was applied to measure vibrational characteristics of magnetic head slider of hard disk drives and to measure stator teeth driving velocities of ultrasonic motor.

  14. RESEARCH OF BRIDGE STRUCTURE VIBRATION CHARACTERISTICS

    Directory of Open Access Journals (Sweden)

    V.P. Babak

    2005-02-01

    Full Text Available  Bridge structure test results with using different types of dynamic force have been considered. It has been shown, that the developed technique of registering and processing vibration signals allows obtaining thin spectrum structure. The analysis of its change that is defined by the type of structure loading applied has been carried out. Key parameters of the vibration signals registered have been defined.

  15. Aircraft gas turbine engine vibration diagnostics

    OpenAIRE

    Stanislav Fábry; Marek Češkovič

    2017-01-01

    In the Czech and Slovak aviation are in service elderly aircrafts, usually produced in former Soviet Union. Their power units can be operated in more efficient way, in case of using additional diagnostic methods that allow evaluating their health. Vibration diagnostics is one of the methods indicating changes of rotational machine dynamics. Ground tests of aircraft gas turbine engines allow vibration recording and analysis. Results contribute to airworthiness evaluation and making corrections...

  16. Issues in vibration energy harvesting

    Science.gov (United States)

    Zhang, Hui; Corr, Lawrence R.; Ma, Tianwei

    2018-05-01

    In this study, fundamental issues related to bandwidth and nonlinear resonance in vibrational energy harvesting devices are investigated. The results show that using bandwidth as a criterion to measure device performance can be misleading. For a linear device, an enlarged bandwidth is achieved at the cost of sacrificing device performance near resonance, and thus widening the bandwidth may offer benefits only when the natural frequency of the linear device cannot match the dominant excitation frequency. For a nonlinear device, since the principle of superposition does not apply, the ''broadband" performance improvements achieved for single-frequency excitations may not be achievable for multi-frequency excitations. It is also shown that a large-amplitude response based on the traditional ''nonlinear resonance" does not always result in the optimal performance for a nonlinear device because of the negative work done by the excitation, which indicates energy is returned back to the excitation. Such undesired negative work is eliminated at global resonance, a generalized resonant condition for both linear and nonlinear systems. While the linear resonance is a special case of global resonance for a single-frequency excitation, the maximum potential of nonlinear energy harvesting can be reached for multi-frequency excitations by using global resonance to simultaneously harvest energy distributed over multiple frequencies.

  17. No Telescoping Effect with Dual Tendon Vibration.

    Directory of Open Access Journals (Sweden)

    Valeria Bellan

    Full Text Available The tendon vibration illusion has been extensively used to manipulate the perceived position of one's own body part. However, findings from previous research do not seem conclusive sregarding the perceptual effect of the concurrent stimulation of both agonist and antagonist tendons over one joint. On the basis of recent data, it has been suggested that this paired stimulation generates an inconsistent signal about the limb position, which leads to a perceived shrinkage of the limb. However, this interesting effect has never been replicated. The aim of the present study was to clarify the effect of a simultaneous and equal vibration of the biceps and triceps tendons on the perceived location of the hand. Experiment 1 replicated and extended the previous findings. We compared a dual tendon stimulation condition with single tendon stimulation conditions and with a control condition (no vibration on both 'upward-downward' and 'towards-away from the elbow' planes. Our results show a mislocalisation towards the elbow of the position of the vibrated arm during dual vibration, in line with previous results; however, this did not clarify whether the effect was due to arm representation contraction (i.e., a 'telescoping' effect. Therefore, in Experiment 2 we investigated explicitly and implicitly the perceived arm length during the same conditions. Our results clearly suggest that in all the vibration conditions there was a mislocalisation of the entire arm (including the elbow, but no evidence of a contraction of the perceived arm length.

  18. Quantum Monte Carlo for vibrating molecules

    International Nuclear Information System (INIS)

    Brown, W.R.; Lawrence Berkeley National Lab., CA

    1996-08-01

    Quantum Monte Carlo (QMC) has successfully computed the total electronic energies of atoms and molecules. The main goal of this work is to use correlation function quantum Monte Carlo (CFQMC) to compute the vibrational state energies of molecules given a potential energy surface (PES). In CFQMC, an ensemble of random walkers simulate the diffusion and branching processes of the imaginary-time time dependent Schroedinger equation in order to evaluate the matrix elements. The program QMCVIB was written to perform multi-state VMC and CFQMC calculations and employed for several calculations of the H 2 O and C 3 vibrational states, using 7 PES's, 3 trial wavefunction forms, two methods of non-linear basis function parameter optimization, and on both serial and parallel computers. In order to construct accurate trial wavefunctions different wavefunctions forms were required for H 2 O and C 3 . In order to construct accurate trial wavefunctions for C 3 , the non-linear parameters were optimized with respect to the sum of the energies of several low-lying vibrational states. In order to stabilize the statistical error estimates for C 3 the Monte Carlo data was collected into blocks. Accurate vibrational state energies were computed using both serial and parallel QMCVIB programs. Comparison of vibrational state energies computed from the three C 3 PES's suggested that a non-linear equilibrium geometry PES is the most accurate and that discrete potential representations may be used to conveniently determine vibrational state energies

  19. Vibrational polarizabilities of hydrogen-bonded water

    International Nuclear Information System (INIS)

    Torii, Hajime

    2013-01-01

    Highlights: ► Vibrational polarizabilities of hydrogen-bonded water are analyzed theoretically. ► Total vibrational polarizability is (at least) comparable to the electronic one. ► Molecular translations contribute to the vibrational polarizability below 300 cm −1 . ► Intermolecular charge fluxes along H bonds are induced by molecular translations. ► The results are discussed in relation to the observed dielectric properties. - Abstract: The vibrational polarizabilities and the related molecular properties of hydrogen-bonded water are analyzed theoretically, taking the case of (water) 30 clusters as an example case. It is shown that some off-diagonal dipole derivatives are large for the translations of incompletely hydrogen-bonded molecules, and this is reasonably explained by the scheme of intermolecular charge fluxes induced along hydrogen bonds. In total, because of these intermolecular charge fluxes, molecular translations give rise to the vibrational polarizability of 2.8–3.3 a 0 3 per molecule, which is as large as about 40% of the electronic polarizability, mainly in the frequency region below 300 cm −1 . Adding the contributions of the molecular rotations (librations) and the translation–rotation cross term, the total polarizability (electronic + vibrational) at ∼100 cm −1 is slightly larger than the double of that at >4000 cm −1 . The relation of these results to some observed time- and frequency-dependent dielectric properties of liquid water is briefly discussed

  20. Broadband Vibration Attenuation Using Hybrid Periodic Rods

    Directory of Open Access Journals (Sweden)

    S. Asiri

    2008-12-01

    Full Text Available This paper presents both theoretically and experimentally a new kind of a broadband vibration isolator. It is a table-like system formed by four parallel hybrid periodic rods connected between two plates. The rods consist of an assembly of periodic cells, each cell being composed of a short rod and piezoelectric inserts. By actively controlling the piezoelectric elements, it is shown that the periodic rods can efficiently attenuate the propagation of vibration from the upper plate to the lower one within critical frequency bands and consequently minimize the effects of transmission of undesirable vibration and sound radiation. In such a system, longitudinal waves can propagate from the vibration source in the upper plate to the lower one along the rods only within specific frequency bands called the "Pass Bands" and wave propagation is efficiently attenuated within other frequency bands called the "Stop Bands". The spectral width of these bands can be tuned according to the nature of the external excitation. The theory governing the operation of this class of vibration isolator is presented and their tunable filtering characteristics are demonstrated experimentally as functions of their design parameters. This concept can be employed in many applications to control the wave propagation and the force transmission of longitudinal vibrations both in the spectral and spatial domains in an attempt to stop/attenuate the propagation of undesirable disturbances.

  1. Frequency adjustable MEMS vibration energy harvester

    Science.gov (United States)

    Podder, P.; Constantinou, P.; Amann, A.; Roy, S.

    2016-10-01

    Ambient mechanical vibrations offer an attractive solution for powering the wireless sensor nodes of the emerging “Internet-of-Things”. However, the wide-ranging variability of the ambient vibration frequencies pose a significant challenge to the efficient transduction of vibration into usable electrical energy. This work reports the development of a MEMS electromagnetic vibration energy harvester where the resonance frequency of the oscillator can be adjusted or tuned to adapt to the ambient vibrational frequency. Micro-fabricated silicon spring and double layer planar micro-coils along with sintered NdFeB micro-magnets are used to construct the electromagnetic transduction mechanism. Furthermore, another NdFeB magnet is adjustably assembled to induce variable magnetic interaction with the transducing magnet, leading to significant change in the spring stiffness and resonance frequency. Finite element analysis and numerical simulations exhibit substantial frequency tuning range (25% of natural resonance frequency) by appropriate adjustment of the repulsive magnetic interaction between the tuning and transducing magnet pair. This demonstrated method of frequency adjustment or tuning have potential applications in other MEMS vibration energy harvesters and micromechanical oscillators.

  2. Vibrational spectroscopy in the electron microscope.

    Science.gov (United States)

    Krivanek, Ondrej L; Lovejoy, Tracy C; Dellby, Niklas; Aoki, Toshihiro; Carpenter, R W; Rez, Peter; Soignard, Emmanuel; Zhu, Jiangtao; Batson, Philip E; Lagos, Maureen J; Egerton, Ray F; Crozier, Peter A

    2014-10-09

    Vibrational spectroscopies using infrared radiation, Raman scattering, neutrons, low-energy electrons and inelastic electron tunnelling are powerful techniques that can analyse bonding arrangements, identify chemical compounds and probe many other important properties of materials. The spatial resolution of these spectroscopies is typically one micrometre or more, although it can reach a few tens of nanometres or even a few ångströms when enhanced by the presence of a sharp metallic tip. If vibrational spectroscopy could be combined with the spatial resolution and flexibility of the transmission electron microscope, it would open up the study of vibrational modes in many different types of nanostructures. Unfortunately, the energy resolution of electron energy loss spectroscopy performed in the electron microscope has until now been too poor to allow such a combination. Recent developments that have improved the attainable energy resolution of electron energy loss spectroscopy in a scanning transmission electron microscope to around ten millielectronvolts now allow vibrational spectroscopy to be carried out in the electron microscope. Here we describe the innovations responsible for the progress, and present examples of applications in inorganic and organic materials, including the detection of hydrogen. We also demonstrate that the vibrational signal has both high- and low-spatial-resolution components, that the first component can be used to map vibrational features at nanometre-level resolution, and that the second component can be used for analysis carried out with the beam positioned just outside the sample--that is, for 'aloof' spectroscopy that largely avoids radiation damage.

  3. The vibration compensation system for ARGOS

    Science.gov (United States)

    Peter, D.; Gaessler, W.; Borelli, J.; Kulas, M.

    2011-09-01

    For every adaptive optics system telescope vibrations can strongly reduce the performance. This is true for the receiver part of the system i.e. the telescope and wave front sensor part as well as for the transmitter part in the case of a laser guide star system. Especially observations in deep fields observed with a laser guide star system without any tip-tilt star will be greatly spoiled by telescope vibrations. The ARGOS GLAO system actually being built for the LBT aims to implement this kind of mode where wave front correction will rely purely on signals from the laser beacons. To remove the vibrations from the uplink path a vibration compensation system will be installed. This system uses accelerometers to measure the vibrations and corrects their effect with a small fast tip-tilt mirror. The controller of the system is built based on the assumption that the vibrations take place at a few distinct frequencies. Here I present a lab set-up of this system and show first results of the performance.

  4. Vibration monitoring with artificial neural networks

    International Nuclear Information System (INIS)

    Alguindigue, I.

    1991-01-01

    Vibration monitoring of components in nuclear power plants has been used for a number of years. This technique involves the analysis of vibration data coming from vital components of the plant to detect features which reflect the operational state of machinery. The analysis leads to the identification of potential failures and their causes, and makes it possible to perform efficient preventive maintenance. Earlydetection is important because it can decrease the probability of catastrophic failures, reduce forced outgage, maximize utilization of available assets, increase the life of the plant, and reduce maintenance costs. This paper documents our work on the design of a vibration monitoring methodology based on neural network technology. This technology provides an attractive complement to traditional vibration analysis because of the potential of neural network to operate in real-time mode and to handle data which may be distorted or noisy. Our efforts have been concentrated on the analysis and classification of vibration signatures collected from operating machinery. Two neural networks algorithms were used in our project: the Recirculation algorithm for data compression and the Backpropagation algorithm to perform the actual classification of the patterns. Although this project is in the early stages of development it indicates that neural networks may provide a viable methodology for monitoring and diagnostics of vibrating components. Our results to date are very encouraging

  5. Behavior of Cell on Vibrating Micro Ridges

    Directory of Open Access Journals (Sweden)

    Haruka Hino

    2015-06-01

    Full Text Available The effect of micro ridges on cells cultured at a vibrating scaffold has been studied in vitro. Several parallel lines of micro ridges have been made on a disk of transparent polydimethylsiloxane for a scaffold. To apply the vibration on the cultured cells, a piezoelectric element was attached on the outside surface of the bottom of the scaffold. The piezoelectric element was vibrated by the sinusoidal alternating voltage (Vp-p < 16 V at 1.0 MHz generated by a function generator. Four kinds of cells were used in the test: L929 (fibroblast connective tissue of C3H mouse, Hepa1-6 (mouse hepatoma, C2C12 (mouse myoblast, 3T3-L1 (mouse fat precursor cells. The cells were seeded on the micro pattern at the density of 2000 cells/cm2 in the medium containing 10% FBS (fetal bovine serum and 1% penicillin/ streptomycin. After the adhesion of cells in several hours, the cells are exposed to the ultrasonic vibration for several hours. The cells were observed with a phase contrast microscope. The experimental results show that the cells adhere, deform and migrate on the scaffold with micro patterns regardless of the ultrasonic vibration. The effects of the vibration and the micro pattern depend on the kind of cells.

  6. Frequency adjustable MEMS vibration energy harvester

    International Nuclear Information System (INIS)

    Podder, P; Constantinou, P; Roy, S; Amann, A

    2016-01-01

    Ambient mechanical vibrations offer an attractive solution for powering the wireless sensor nodes of the emerging “Internet-of-Things”. However, the wide-ranging variability of the ambient vibration frequencies pose a significant challenge to the efficient transduction of vibration into usable electrical energy. This work reports the development of a MEMS electromagnetic vibration energy harvester where the resonance frequency of the oscillator can be adjusted or tuned to adapt to the ambient vibrational frequency. Micro-fabricated silicon spring and double layer planar micro-coils along with sintered NdFeB micro-magnets are used to construct the electromagnetic transduction mechanism. Furthermore, another NdFeB magnet is adjustably assembled to induce variable magnetic interaction with the transducing magnet, leading to significant change in the spring stiffness and resonance frequency. Finite element analysis and numerical simulations exhibit substantial frequency tuning range (25% of natural resonance frequency) by appropriate adjustment of the repulsive magnetic interaction between the tuning and transducing magnet pair. This demonstrated method of frequency adjustment or tuning have potential applications in other MEMS vibration energy harvesters and micromechanical oscillators. (paper)

  7. Method and apparatus for vibrating a substrate during material formation

    Science.gov (United States)

    Bailey, Jeffrey A [Richland, WA; Roger, Johnson N [Richland, WA; John, Munley T [Benton City, WA; Walter, Park R [Benton City, WA

    2008-10-21

    A method and apparatus for affecting the properties of a material include vibrating the material during its formation (i.e., "surface sifting"). The method includes the steps of providing a material formation device and applying a plurality of vibrations to the material during formation, which vibrations are oscillations having dissimilar, non-harmonic frequencies and at least two different directions. The apparatus includes a plurality of vibration sources that impart vibrations to the material.

  8. Using piezo-electric material to simulate a vibration environment

    Science.gov (United States)

    Jepsen, Richard A.; Davie, Neil T.; Vangoethem, Douglas J.; Romero, Edward F.

    2010-12-14

    A target object can be vibrated using actuation that exploits the piezo-electric ("PE") property. Under combined conditions of vibration and centrifugal acceleration, a centrifugal load of the target object on PE vibration actuators can be reduced by using a counterweight that offsets the centrifugal loading. Target objects are also subjected to combinations of: spin, vibration, and acceleration; spin and vibration; and spin and acceleration.

  9. Vibration Analysis of Beam and Block Precast Slab System due to Human Vibrations

    Science.gov (United States)

    Chik, T. N. T.; Kamil, M. R. H.; Yusoff, N. A.

    2018-04-01

    Beam and block precast slabs system are very efficient which generally give maximum structural performance where their voids based on the design of the unit soffit block allow a significant reduction of the whole slab self-weight. Initially for some combinations of components or the joint connection of the structural slab, this structural system may be susceptible to excessive vibrations that could effects the performance and also serviceability. Dynamic forces are excited from people walking and jumping which produced vibrations to the slab system in the buildings. Few studies concluded that human induced vibration on precast slabs system may be harmful to structural performance and mitigate the human comfort level. This study will investigate the vibration analysis of beam and block precast slab by using finite element method at the school building. Human activities which are excited from jumping and walking will induce the vibrations signal to the building. Laser Doppler Vibrometer (LDV) was used to measure the dynamic responses of slab towards the vibration sources. Five different points were assigned specifically where each of location will determine the behaviour of the entire slabs. The finite element analyses were developed in ABAQUS software and the data was further processed in MATLAB ModalV to assess the vibration criteria. The results indicated that the beam and block precast systems adequate enough to the vibration serviceability and human comfort criteria. The overall vibration level obtained was fell under VC-E curve which it is generally under the maximum permissible level of vibrations. The vibration level on the slab is acceptable within the limit that have been used by Gordon.

  10. Two-dimensional vibrational-electronic spectroscopy

    Science.gov (United States)

    Courtney, Trevor L.; Fox, Zachary W.; Slenkamp, Karla M.; Khalil, Munira

    2015-10-01

    Two-dimensional vibrational-electronic (2D VE) spectroscopy is a femtosecond Fourier transform (FT) third-order nonlinear technique that creates a link between existing 2D FT spectroscopies in the vibrational and electronic regions of the spectrum. 2D VE spectroscopy enables a direct measurement of infrared (IR) and electronic dipole moment cross terms by utilizing mid-IR pump and optical probe fields that are resonant with vibrational and electronic transitions, respectively, in a sample of interest. We detail this newly developed 2D VE spectroscopy experiment and outline the information contained in a 2D VE spectrum. We then use this technique and its single-pump counterpart (1D VE) to probe the vibrational-electronic couplings between high frequency cyanide stretching vibrations (νCN) and either a ligand-to-metal charge transfer transition ([FeIII(CN)6]3- dissolved in formamide) or a metal-to-metal charge transfer (MMCT) transition ([(CN)5FeIICNRuIII(NH3)5]- dissolved in formamide). The 2D VE spectra of both molecules reveal peaks resulting from coupled high- and low-frequency vibrational modes to the charge transfer transition. The time-evolving amplitudes and positions of the peaks in the 2D VE spectra report on coherent and incoherent vibrational energy transfer dynamics among the coupled vibrational modes and the charge transfer transition. The selectivity of 2D VE spectroscopy to vibronic processes is evidenced from the selective coupling of specific νCN modes to the MMCT transition in the mixed valence complex. The lineshapes in 2D VE spectra report on the correlation of the frequency fluctuations between the coupled vibrational and electronic frequencies in the mixed valence complex which has a time scale of 1 ps. The details and results of this study confirm the versatility of 2D VE spectroscopy and its applicability to probe how vibrations modulate charge and energy transfer in a wide range of complex molecular, material, and biological systems.

  11. Two-dimensional vibrational-electronic spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Courtney, Trevor L.; Fox, Zachary W.; Slenkamp, Karla M.; Khalil, Munira, E-mail: mkhalil@uw.edu [Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195 (United States)

    2015-10-21

    Two-dimensional vibrational-electronic (2D VE) spectroscopy is a femtosecond Fourier transform (FT) third-order nonlinear technique that creates a link between existing 2D FT spectroscopies in the vibrational and electronic regions of the spectrum. 2D VE spectroscopy enables a direct measurement of infrared (IR) and electronic dipole moment cross terms by utilizing mid-IR pump and optical probe fields that are resonant with vibrational and electronic transitions, respectively, in a sample of interest. We detail this newly developed 2D VE spectroscopy experiment and outline the information contained in a 2D VE spectrum. We then use this technique and its single-pump counterpart (1D VE) to probe the vibrational-electronic couplings between high frequency cyanide stretching vibrations (ν{sub CN}) and either a ligand-to-metal charge transfer transition ([Fe{sup III}(CN){sub 6}]{sup 3−} dissolved in formamide) or a metal-to-metal charge transfer (MMCT) transition ([(CN){sub 5}Fe{sup II}CNRu{sup III}(NH{sub 3}){sub 5}]{sup −} dissolved in formamide). The 2D VE spectra of both molecules reveal peaks resulting from coupled high- and low-frequency vibrational modes to the charge transfer transition. The time-evolving amplitudes and positions of the peaks in the 2D VE spectra report on coherent and incoherent vibrational energy transfer dynamics among the coupled vibrational modes and the charge transfer transition. The selectivity of 2D VE spectroscopy to vibronic processes is evidenced from the selective coupling of specific ν{sub CN} modes to the MMCT transition in the mixed valence complex. The lineshapes in 2D VE spectra report on the correlation of the frequency fluctuations between the coupled vibrational and electronic frequencies in the mixed valence complex which has a time scale of 1 ps. The details and results of this study confirm the versatility of 2D VE spectroscopy and its applicability to probe how vibrations modulate charge and energy transfer in a

  12. Entropy for Mechanically Vibrating Systems

    Science.gov (United States)

    Tufano, Dante

    The research contained within this thesis deals with the subject of entropy as defined for and applied to mechanically vibrating systems. This work begins with an overview of entropy as it is understood in the fields of classical thermodynamics, information theory, statistical mechanics, and statistical vibroacoustics. Khinchin's definition of entropy, which is the primary definition used for the work contained in this thesis, is introduced in the context of vibroacoustic systems. The main goal of this research is to to establish a mathematical framework for the application of Khinchin's entropy in the field of statistical vibroacoustics by examining the entropy context of mechanically vibrating systems. The introduction of this thesis provides an overview of statistical energy analysis (SEA), a modeling approach to vibroacoustics that motivates this work on entropy. The objective of this thesis is given, and followed by a discussion of the intellectual merit of this work as well as a literature review of relevant material. Following the introduction, an entropy analysis of systems of coupled oscillators is performed utilizing Khinchin's definition of entropy. This analysis develops upon the mathematical theory relating to mixing entropy, which is generated by the coupling of vibroacoustic systems. The mixing entropy is shown to provide insight into the qualitative behavior of such systems. Additionally, it is shown that the entropy inequality property of Khinchin's entropy can be reduced to an equality using the mixing entropy concept. This equality can be interpreted as a facet of the second law of thermodynamics for vibroacoustic systems. Following this analysis, an investigation of continuous systems is performed using Khinchin's entropy. It is shown that entropy analyses using Khinchin's entropy are valid for continuous systems that can be decomposed into a finite number of modes. The results are shown to be analogous to those obtained for simple oscillators

  13. Vibrational properties of complex solids

    International Nuclear Information System (INIS)

    Fagas, G.

    1999-11-01

    Following a brief outline of the statistical analysis of spectra with respect to random matrix theory predictions and of numerical methods for calculating the elastic scattering matrix, statistical studies of vibrational spectra in disordered and complex solids, as well as studies of phonon transport across imperfect structures, are presented. The analysis of spectral statistics of lattice modes in a disordered crystal, confirmed GOE Wigner-Dyson statistical correlations of the eigenmode frequencies of a block of a disordered solid. Spectral correlations in the optic phonon spectrum of a solid with a polyatomic unit cell are also analysed using the Wigner-Dyson statistical approach. Despite the fact that all force constants are real, it is demonstrated that the statistics are predominantly of the GUE type depending on the location within the Brillouin zone of a crystal and the unit cell symmetry. Analytic and numerical results for the crossover from GOE to GUE statistics are presented. A method originally developed to probe electron transport on a mesoscopic scale is used to study generic properties of elastic phonon transport at a disordered interface. The results show that phonon transmittance is a strong function of frequency and the disorder correlation length. At low frequencies the transmittance at a given frequency increases as the correlation length decreases. This is also reflected by different power-laws for phonon conductance across correlated and uncorrelated disordered interfaces which are in approximate agreement with perturbation theory of an elastic continuum. Finally we present an analysis of acoustic-phonon propagation across long, free-standing, insulating wires with rough surfaces. We find that owing to a crossover from ballistic propagation of the lowest-frequency phonon mode at ω 1 πc/W to a diffusive (or even localized) behavior upon the increase of phonon frequency, followed by reentrance into the quasiballistic regime, the heat

  14. Vibration transfers to measure the performance of vibration isolated platforms on site using background noise excitation

    NARCIS (Netherlands)

    Segerink, Franciscus B.; Korterik, Jeroen P.; Offerhaus, Herman L.

    2011-01-01

    This article demonstrates a quick and easy way of quantifying the performance of a vibration-isolated platform. We measure the vibration transfer from floor to table using background noise excitation from the floor. As no excitation device is needed, our setup only requires two identical sensors (in

  15. Implausibility of the vibrational theory of olfaction.

    Science.gov (United States)

    Block, Eric; Jang, Seogjoo; Matsunami, Hiroaki; Sekharan, Sivakumar; Dethier, Bérénice; Ertem, Mehmed Z; Gundala, Sivaji; Pan, Yi; Li, Shengju; Li, Zhen; Lodge, Stephene N; Ozbil, Mehmet; Jiang, Huihong; Penalba, Sonia F; Batista, Victor S; Zhuang, Hanyi

    2015-05-26

    The vibrational theory of olfaction assumes that electron transfer occurs across odorants at the active sites of odorant receptors (ORs), serving as a sensitive measure of odorant vibrational frequencies, ultimately leading to olfactory perception. A previous study reported that human subjects differentiated hydrogen/deuterium isotopomers (isomers with isotopic atoms) of the musk compound cyclopentadecanone as evidence supporting the theory. Here, we find no evidence for such differentiation at the molecular level. In fact, we find that the human musk-recognizing receptor, OR5AN1, identified using a heterologous OR expression system and robustly responding to cyclopentadecanone and muscone, fails to distinguish isotopomers of these compounds in vitro. Furthermore, the mouse (methylthio)methanethiol-recognizing receptor, MOR244-3, as well as other selected human and mouse ORs, responded similarly to normal, deuterated, and (13)C isotopomers of their respective ligands, paralleling our results with the musk receptor OR5AN1. These findings suggest that the proposed vibration theory does not apply to the human musk receptor OR5AN1, mouse thiol receptor MOR244-3, or other ORs examined. Also, contrary to the vibration theory predictions, muscone-d30 lacks the 1,380- to 1,550-cm(-1) IR bands claimed to be essential for musk odor. Furthermore, our theoretical analysis shows that the proposed electron transfer mechanism of the vibrational frequencies of odorants could be easily suppressed by quantum effects of nonodorant molecular vibrational modes. These and other concerns about electron transfer at ORs, together with our extensive experimental data, argue against the plausibility of the vibration theory.

  16. Nonlinear Response of Vibrational Conveyers with Nonideal Vibration Exciter: Superharmonic and Subharmonic Resonance

    Directory of Open Access Journals (Sweden)

    H. Bayıroğlu

    2012-01-01

    Full Text Available Vibrational conveyers with a centrifugal vibration exciter transmit their load based on the jumping method. Common unbalanced-mass driver oscillates the trough. The motion is strictly related to the vibrational parameters. The transition over resonance of a vibratory system, excited by rotating unbalances, is important in terms of the maximum vibrational amplitude produced and the power demand on the drive for the crossover. The mechanical system is driven by the DC motor. In this study, the working ranges of oscillating shaking conveyers with nonideal vibration exciter have been analyzed analytically for superharmonic and subharmonic resonances by the method of multiple scales and numerically. The analytical results obtained in this study agree well with the numerical results.

  17. Collision dynamics of methyl radicals and highly vibrationally excited molecules using crossed molecular beams

    International Nuclear Information System (INIS)

    Chu, P.M.Y.

    1991-10-01

    The vibrational to translational (V→T) energy transfer in collisions between large highly vibrationally excited polyatomics and rare gases was investigated by time-of-flight techniques. Two different methods, UV excitation followed by intemal conversion and infrared multiphoton excitation (IRMPE), were used to form vibrationally excited molecular beams of hexafluorobenzene and sulfur hexafluoride, respectively. The product translational energy was found to be independent of the vibrational excitation. These results indicate that the probability distribution function for V→T energy transfer is peaked at zero. The collisional relaxation of large polyatomic molecules with rare gases most likely occurs through a rotationally mediated process. Photodissociation of nitrobenzene in a molecular beam was studied at 266 nm. Two primary dissociation channels were identified including simple bond rupture to produce nitrogen dioxide and phenyl radical and isomerization to form nitric oxide and phenoxy radical. The time-of-flight spectra indicate that simple bond rupture and isomerization occurs via two different mechanisms. Secondary dissociation of the phenoxy radicals to carbon monoxide and cyclopentadienyl radicals was observed as well as secondary photodissociation of phenyl radical to give H atom and benzyne. A supersonic methyl radical beam source is developed. The beam source configuration and conditions were optimized for CH 3 production from the thermal decomposition of azomethane. Elastic scattering of methyl radical and neon was used to differentiate between the methyl radicals and the residual azomethane in the molecular beam

  18. Prolonged maintenance of capsaicin-induced hyperalgesia by brief daily vibration stimuli.

    Science.gov (United States)

    Kim, Hee Kee; Schattschneider, Jörn; Lee, Inhyung; Chung, Kyungsoon; Baron, Ralf; Chung, Jin Mo

    2007-05-01

    This study tests the hypothesis that central sensitization initiated by nociceptive input can be maintained by repeated brief innocuous peripheral inputs. Capsaicin was injected intradermally into the hind paw of adult rats. Three different types of daily cutaneous mechanical stimulations (vibration, soft brush, or pressure) were applied to the capsaicin-injected paw for a period of 2 weeks. Daily stimulation consisted of a 10-s stimulation repeated every 30s for 30 min. Foot withdrawal thresholds to von Frey stimuli applied to the paw were measured once a day for 4 weeks. The capsaicin-only group (control rats without daily stimulation) showed hyperalgesia lasting for 3 days. In contrast, hyperalgesia persisted for 2 weeks in the group that received vibration stimulation. Neither the soft brush nor the pressure group showed a significant difference in mechanical threshold from the control group (capsaicin only). The vibration-induced prolonged hyperalgesia was significantly reduced by systemic injection of ifenprodil, an NMDA-receptor antagonist, but it was not influenced by either an AMPA-receptor blocker or a reactive oxygen species (ROS) scavenger. Furthermore, a dorsal column lesion did not interfere with the prolongation of hyperalgesia. Data suggest that vibration-induced prolongation of hyperalgesia is mediated by spinal NMDA-receptors, and a similar mechanism may underlie some forms of chronic pain with no obvious causes, such as complex regional pain syndrome type 1 (CRPS-1).

  19. Construction of a Vibration Monitoring System for HANARO's Rotating Machinery and Analysis of Pump Vibration Signals

    International Nuclear Information System (INIS)

    Ryu, Jeong Soo; Yoon, Doo Byung

    2005-01-01

    HANARO is an open-tank-in-pool type research reactor with a thermal power of 30MW. In order to remove the heat generated by the reactor core and the reflector vessel, primary cooling pumps and reflector cooling pumps circulate coolant. These pumps are installed at the RCI(Reactor Concrete Island) which is covered by heavy concrete hatches. For the prevention of an abnormal operation of these pumps in the RCI, it is necessary to construct a vibration monitoring system that provides an alarm signal to the reactor control room when the rotating speed or the vibration level exceeds the allowable limit. The first objective of this work is to construct a vibration monitoring system for HANARO's rotating machinery. The second objective is to verify the possibility of condition monitoring of the rotating machinery. To construct a vibration monitoring system, as a first step, the standards and references related to the vibration monitoring system were investigated. In addition, to determine the number and the location of sensors that can effectively characterize the overall vibration of a pump, the vibration of the primary cooling pumps and the reflector cooling pumps were measured. Based on these results, detailed construction plans for the vibration monitoring system for HANARO were established. Then, in accordance with the construction plans, the vibration monitoring system for HANARO's rotating machinery was manufactured and installed at HANARO. To achieve the second objective, FFT analysis and bearing fault detection of the measured vibration signals were performed. The analysis results demonstrate that the accelerometers mounted at the bearing locations of the pumps can effectively monitor the pump condition

  20. Design of a nonlinear torsional vibration absorber

    Science.gov (United States)

    Tahir, Ammaar Bin

    Tuned mass dampers (TMD) utilizing linear spring mechanisms to mitigate destructive vibrations are commonly used in practice. A TMD is usually tuned for a specific resonant frequency or an operating frequency of a system. Recently, nonlinear vibration absorbers attracted attention of researchers due to some potential advantages they possess over the TMDs. The nonlinear vibration absorber, or the nonlinear energy sink (NES), has an advantage of being effective over a broad range of excitation frequencies, which makes it more suitable for systems with several resonant frequencies, or for a system with varying excitation frequency. Vibration dissipation mechanism in an NES is passive and ensures that there is no energy backflow to the primary system. In this study, an experimental setup of a rotational system has been designed for validation of the concept of nonlinear torsional vibration absorber with geometrically induced cubic stiffness nonlinearity. Dimensions of the primary system have been optimized so as to get the first natural frequency of the system to be fairly low. This was done in order to excite the dynamic system for torsional vibration response by the available motor. Experiments have been performed to obtain the modal parameters of the system. Based on the obtained modal parameters, the design optimization of the nonlinear torsional vibration absorber was carried out using an equivalent 2-DOF modal model. The optimality criterion was chosen to be maximization of energy dissipation in the nonlinear absorber attached to the equivalent 2-DOF system. The optimized design parameters of the nonlinear absorber were tested on the original 5-DOF system numerically. A comparison was made between the performance of linear and nonlinear absorbers using the numerical models. The comparison showed the superiority of the nonlinear absorber over its linear counterpart for the given set of primary system parameters as the vibration energy dissipation in the former is

  1. Vibration Isolation for Parallel Hydraulic Hybrid Vehicles

    Directory of Open Access Journals (Sweden)

    The M. Nguyen

    2008-01-01

    Full Text Available In recent decades, several types of hybrid vehicles have been developed in order to improve the fuel economy and to reduce the pollution. Hybrid electric vehicles (HEV have shown a significant improvement in fuel efficiency for small and medium-sized passenger vehicles and SUVs. HEV has several limitations when applied to heavy vehicles; one is that larger vehicles demand more power, which requires significantly larger battery capacities. As an alternative solution, hydraulic hybrid technology has been found effective for heavy duty vehicle because of its high power density. The mechanical batteries used in hydraulic hybrid vehicles (HHV can be charged and discharged remarkably faster than chemical batteries. This feature is essential for heavy vehicle hybridization. One of the main problems that should be solved for the successful commercialization of HHV is the excessive noise and vibration involving with the hydraulic systems. This study focuses on using magnetorheological (MR technology to reduce the noise and vibration transmissibility from the hydraulic system to the vehicle body. In order to study the noise and vibration of HHV, a hydraulic hybrid subsystem in parallel design is analyzed. This research shows that the MR elements play an important role in reducing the transmitted noise and vibration to the vehicle body. Additionally, locations and orientations of the isolation system also affect the efficiency of the noise and vibration mitigation. In simulations, a skyhook control algorithm is used to achieve the highest possible effectiveness of the MR isolation system.

  2. Vibration-proof FBR type reactor

    International Nuclear Information System (INIS)

    Kawamura, Yutaka.

    1992-01-01

    In a reactor container in an FBR type reactor, an outer building and upper and lower portions of a reactor container are connected by a load transmission device made of a laminated material of rubber and steel plates. Each of the reactor container and the outer building is disposed on a lower raft disposed on a rock by way of a vibration-proof device made of a laminated material of rubber and steel plates. Vibration-proof elements for providing vertical eigen frequency of the vibration-proof system comprising the reactor building and the vibration-proof device within a range of 3Hz to 5Hz are used. That is, the peak of designed acceleration for response spectrum in the horizontal direction of the reactor structural portions is shifted to side of shorter period from the main frequency region of the reactor structure. Alternatively, rigidity of the vibration-proof elements is decreased to shift the peak to the side of long period from the main frequency region. Designed seismic force can be greatly reduced both horizontally and vertically, to reduce the wall thickness of the structural members, improve the plant economy and to ensure the safety against earthquakes. (N.H.)

  3. Vibrational characteristics and wear of fuel rods

    International Nuclear Information System (INIS)

    Schmugar, K.L.

    1977-01-01

    Fuel rod wear, due to vibration, is a continuing concern in the design of liquid-cooled reactors. In my report, the methodology and models that are used to predict fuel rod vibrational response and vibratory wear, in a light water reactor environment, are discussed. This methodology is being followed at present in the design of Westinghouse Nuclear Fuel. Fuel rod vibrations are expressed as the normal bending modes, and sources of rod vibration are examined with special emphasis on flow-induced mechanisms in the stable flow region. In a typical Westinghouse PWR fuel assembly design, each fuel rod is supported at multiple locations along the rod axis by a square-shaped 'grid cell'. For a fuel rod /grid support system, the development of small oscillatory motions, due to fluid flow at the rod/grid interface, results in material wear. A theoretical wear mode is developed using the Archard Theory of Adhesive Wear as the basis. Without question certainty, fretting wear becomes a serious problem if it progresses to the stage where the fuel cladding is penetrated and fuel is exposed to the coolant. Westinghouse fuel is designed to minimize fretting wear by limiting the relative motion between the fuel rod and its supports. The wear producing motion between the fuel rod and its supports occurs when the vibration amplitude exceeds the slippage threshold amplitude

  4. Nanoscale piezoelectric vibration energy harvester design

    Science.gov (United States)

    Foruzande, Hamid Reza; Hajnayeb, Ali; Yaghootian, Amin

    2017-09-01

    Development of new nanoscale devices has increased the demand for new types of small-scale energy resources such as ambient vibrations energy harvesters. Among the vibration energy harvesters, piezoelectric energy harvesters (PEHs) can be easily miniaturized and fabricated in micro and nano scales. This change in the dimensions of a PEH leads to a change in its governing equations of motion, and consequently, the predicted harvested energy comparing to a macroscale PEH. In this research, effects of small scale dimensions on the nonlinear vibration and harvested voltage of a nanoscale PEH is studied. The PEH is modeled as a cantilever piezoelectric bimorph nanobeam with a tip mass, using the Euler-Bernoulli beam theory in conjunction with Hamilton's principle. A harmonic base excitation is applied as a model of the ambient vibrations. The nonlocal elasticity theory is used to consider the size effects in the developed model. The derived equations of motion are discretized using the assumed-modes method and solved using the method of multiple scales. Sensitivity analysis for the effect of different parameters of the system in addition to size effects is conducted. The results show the significance of nonlocal elasticity theory in the prediction of system dynamic nonlinear behavior. It is also observed that neglecting the size effects results in lower estimates of the PEH vibration amplitudes. The results pave the way for designing new nanoscale sensors in addition to PEHs.

  5. Vibration behavior of the artificial barrier system

    International Nuclear Information System (INIS)

    Mikoshiba, Tadashi; Ogawa, Nobuyuki; Nakamura, Izuru

    2000-01-01

    This study aims at production of a mimic specimen of artificial barrier, experimental elucidation of influence of seismic motion due to a vibration experiment on the artificial barrier system, and establishment of an evaluating method on its long-term behavior. The study has been carried out under a cooperative study of the National Research Institute for Earth Science and Disaster Prevention and the Japan Nuclear Cycle Development Institute. In 1998 fiscal year, an artificial barrier specimen initiated by crosscut road was produced, and their random wave and actual seismic wave vibrations were carried out to acquire their fundamental data. As a result of the both vibrations, it was found that in a Case 2 specimen of which buffer material was swelled by poured water, the material was integrated with a mimic over-pack to vibrate under judgement of eigen-frequency, maximum acceleration ratio, and so forth on the test results. And, in a Case 1 specimen, it was thought that the mimic over-pack showed an extreme non-linear performance (soft spring) because of reducing eigen-frequency with increase of its vibration level. (G.K.)

  6. Effects of Vibration Therapy in Pediatric Immunizations.

    Science.gov (United States)

    Benjamin, Arika L; Hendrix, Thomas J; Woody, Jacque L

    2016-01-01

    A randomized clinical trial of 100 children (52 boys, 48 girls) ages 2 months to 7 years was conducted to evaluate the effect of vibration therapy without cold analgesia on pain. A convenience sample was recruited at two sites: a publicly funded, free immunization clinic and a private group pediatric practice. Participants were randomly assigned to receive vibration therapy via a specialized vibrating device or standard care. All children regardless of intervention group were allowed to be distracted and soothed by the parent. Pain was evaluated using the FLACC score, which two nurses assessed at three points in time: prior to, during, and after the injection(s). Data were analyzed using a two-independent samples-paired t-test. Results show that vibration therapy had no effect on pain scores in the younger age groups studied (2 months ≤ 1 year, > 1 year ≤ 4 years). In the oldest age group (> 4 to 7 years of age), a heightened pain reading was found in the period from preinjection to post-injection periods (p = 0.045). These results indicate that the addition of vibration therapy (without cold analgesia) to standard soothing techniques is no more effective in reducing immunization pain than standard soothing techniques alone, and thus, is not indicated for use with immunization pain. Recommendations include further evaluation of interventions.

  7. Vibration behavior of the artificial barrier system

    Energy Technology Data Exchange (ETDEWEB)

    Mikoshiba, Tadashi; Ogawa, Nobuyuki; Nakamura, Izuru [National Research Inst. for Earth sceince and Disaster Prevention (Japan)

    2000-02-01

    This study aims at production of a mimic specimen of artificial barrier, experimental elucidation of influence of seismic motion due to a vibration experiment on the artificial barrier system, and establishment of an evaluating method on its long-term behavior. The study has been carried out under a cooperative study of the National Research Institute for Earth Science and Disaster Prevention and the Japan Nuclear Cycle Development Institute. In 1998 fiscal year, an artificial barrier specimen initiated by crosscut road was produced, and their random wave and actual seismic wave vibrations were carried out to acquire their fundamental data. As a result of the both vibrations, it was found that in a Case 2 specimen of which buffer material was swelled by poured water, the material was integrated with a mimic over-pack to vibrate under judgement of eigen-frequency, maximum acceleration ratio, and so forth on the test results. And, in a Case 1 specimen, it was thought that the mimic over-pack showed an extreme non-linear performance (soft spring) because of reducing eigen-frequency with increase of its vibration level. (G.K.)

  8. Structural Design Optimization On Thermally Induced Vibration

    International Nuclear Information System (INIS)

    Gu, Yuanxian; Chen, Biaosong; Zhang, Hongwu; Zhao, Guozhong

    2002-01-01

    The numerical method of design optimization for structural thermally induced vibration is originally studied in this paper and implemented in application software JIFEX. The direct and adjoint methods of sensitivity analysis for thermal induced vibration coupled with both linear and nonlinear transient heat conduction is firstly proposed. Based on the finite element method, the structural linear dynamics is treated simultaneously with coupled linear and nonlinear transient heat structural linear dynamics is treated simultaneously with coupled linear and nonlinear transient heat conduction. In the thermal analysis model, the nonlinear heat conduction considered is result from the radiation and temperature-dependent materials. The sensitivity analysis of transient linear and nonlinear heat conduction is performed with the precise time integration method. And then, the sensitivity analysis of structural transient dynamics is performed by the Newmark method. Both the direct method and the adjoint method are employed to derive the sensitivity equations of thermal vibration, and there are two adjoint vectors of structure and heat conduction respectively. The coupling effect of heat conduction on thermal vibration in the sensitivity analysis is particularly investigated. With coupling sensitivity analysis, the optimization model is constructed and solved by the sequential linear programming or sequential quadratic programming algorithm. The methods proposed have been implemented in the application software JIFEX of structural design optimization, and numerical examples are given to illustrate the methods and usage of structural design optimization on thermally induced vibration

  9. Normal vibrations in gallium arsenide

    International Nuclear Information System (INIS)

    Dolling, G.; Waugh, J.L.T.

    1964-01-01

    The triple axis crystal spectrometer at Chalk River has been used to observe coherent slow neutron scattering from a single crystal of pure gallium arsenide at 296 o K. The frequencies of normal modes of vibration propagating in the [ζ00], (ζζζ], and (0ζζ] crystal directions have been determined with a precision of between 1 and 2·5 per cent. A limited number of normal modes have also been studied at 95 and 184 o K. Considerable difficulty was experienced in obtaining welt resolved neutron peaks corresponding to the two non-degenerate optic modes for very small wave-vector, particularly at 296 o K. However, from a comparison of results obtained under various experimental conditions at several different points in reciprocal space, frequencies (units 10 12 c/s) for these modes (at 296 o K) have been assigned: T 8·02±0·08 and L 8·55±02. Other specific normal modes, with their measured frequencies are (a) (1,0,0): TO 7·56 ± 008, TA 2·36 ± 0·015, LO 7·22 ± 0·15, LA 6·80 ± 0·06; (b) (0·5, 0·5, 0·5): TO 7·84 ± 0·12, TA 1·86 ± 0·02, LO 7·15 ± 0·07, LA 6·26 ± 0·10; (c) (0, 0·65, 0·65): optic 8·08 ±0·13, 7·54 ± 0·12 and 6·57 ± 0·11, acoustic 5·58 ± 0·08, 3·42 · 0·06 and 2·36 ± 004. These results are generally slightly lower than the corresponding frequencies for germanium. An analysis in terms of various modifications of the dipole approximation model has been carried out. A feature of this analysis is that the charge on the gallium atom appears to be very small, about +0·04 e. The frequency distribution function has been derived from one of the force models. (author)

  10. Normal vibrations in gallium arsenide

    Energy Technology Data Exchange (ETDEWEB)

    Dolling, G; Waugh, J L T

    1964-07-01

    The triple axis crystal spectrometer at Chalk River has been used to observe coherent slow neutron scattering from a single crystal of pure gallium arsenide at 296{sup o}K. The frequencies of normal modes of vibration propagating in the [{zeta}00], ({zeta}{zeta}{zeta}], and (0{zeta}{zeta}] crystal directions have been determined with a precision of between 1 and 2{center_dot}5 per cent. A limited number of normal modes have also been studied at 95 and 184{sup o}K. Considerable difficulty was experienced in obtaining welt resolved neutron peaks corresponding to the two non-degenerate optic modes for very small wave-vector, particularly at 296{sup o}K. However, from a comparison of results obtained under various experimental conditions at several different points in reciprocal space, frequencies (units 10{sup 12} c/s) for these modes (at 296{sup o}K) have been assigned: T 8{center_dot}02{+-}0{center_dot}08 and L 8{center_dot}55{+-}02. Other specific normal modes, with their measured frequencies are (a) (1,0,0): TO 7{center_dot}56 {+-} 008, TA 2{center_dot}36 {+-} 0{center_dot}015, LO 7{center_dot}22 {+-} 0{center_dot}15, LA 6{center_dot}80 {+-} 0{center_dot}06; (b) (0{center_dot}5, 0{center_dot}5, 0{center_dot}5): TO 7{center_dot}84 {+-} 0{center_dot}12, TA 1{center_dot}86 {+-} 0{center_dot}02, LO 7{center_dot}15 {+-} 0{center_dot}07, LA 6{center_dot}26 {+-} 0{center_dot}10; (c) (0, 0{center_dot}65, 0{center_dot}65): optic 8{center_dot}08 {+-}0{center_dot}13, 7{center_dot}54 {+-} 0{center_dot}12 and 6{center_dot}57 {+-} 0{center_dot}11, acoustic 5{center_dot}58 {+-} 0{center_dot}08, 3{center_dot}42 {center_dot} 0{center_dot}06 and 2{center_dot}36 {+-} 004. These results are generally slightly lower than the corresponding frequencies for germanium. An analysis in terms of various modifications of the dipole approximation model has been carried out. A feature of this analysis is that the charge on the gallium atom appears to be very small, about +0{center_dot}04 e. The

  11. Mechanical vibration to electrical energy converter

    Science.gov (United States)

    Kellogg, Rick Allen [Tijeras, NM; Brotz, Jay Kristoffer [Albuquerque, NM

    2009-03-03

    Electromechanical devices that generate an electrical signal in response to an external source of mechanical vibrations can operate as a sensor of vibrations and as an energy harvester for converting mechanical vibration to electrical energy. The devices incorporate a magnet that is movable through a gap in a ferromagnetic circuit, wherein a coil is wound around a portion of the ferromagnetic circuit. A flexible coupling is used to attach the magnet to a frame for providing alignment of the magnet as it moves or oscillates through the gap in the ferromagnetic circuit. The motion of the magnet can be constrained to occur within a substantially linear range of magnetostatic force that develops due to the motion of the magnet. The devices can have ferromagnetic circuits with multiple arms, an array of magnets having alternating polarity and, encompass micro-electromechanical (MEM) devices.

  12. Isotope separation using vibrationally excited molecules

    International Nuclear Information System (INIS)

    Woodroffe, J.A.; Keck, J.C.

    1977-01-01

    A system for isotope separation or enrichment wherein molecules of a selected isotope type in a flow of molecules of plural isotope types are vibrationally excited and collided with a background gas to provide enhanced diffusivity for the molecules of the selected isotope type permitting their separate collection. The system typically is for the enrichment of uranium using a uranium hexafluoride gas in combination with a noble gas such as argon. The uranium hexafluoride molecules having a specific isotope of uranium are vibrationally excited by laser radiation. The vibrational energy is converted to a translation energy upon collision with a particle of the background gas and the added translation energy enhances the diffusivity of the selected hexafluoride molecules facilitating its condensation on collection surfaces provided for that purpose. This process is periodically interrupted and the cryogenic flow halted to permit evaporation of the collected molecules to provide a distinct, enriched flow

  13. Force Limited Vibration Test of HESSI Imager

    Science.gov (United States)

    Amato, Deborah; Pankow, David; Thomsen, Knud

    2000-01-01

    The High Energy Solar Spectroscopic Imager (HESSI) is a solar x-ray and gamma-ray observatory scheduled for launch in November 2000. Vibration testing of the HESSI imager flight unit was performed in August 1999. The HESSI imager consists of a composite metering tube, two aluminum trays mounted to the tube on titanium flexure mounts, and nine modulation grids mounted on each tray. The vibration tests were acceleration controlled and force limited, in order to prevent overtesting. The force limited strategy reduced the shaker force and notched the acceleration at resonances. The test set-up, test levels, and results are presented. The development of the force limits is also discussed. The imager successfully survived the vibration testing.

  14. Status of the Vibrational Theory of Olfaction

    Science.gov (United States)

    Hoehn, Ross D.; Nichols, David E.; Neven, Hartmut; Kais, Sabre

    2018-03-01

    The vibrational theory of olfaction is an attempt to describe a possible mechanism for olfaction which is explanatory and provides researchers with a set of principles which permit predictions allowing for structure-odor relations. Similar theories have occurred several times throughout olfactory science; this theory has again recently come to prominence by Luca Turin who suggested that inelastic electron tunneling is the method by which vibrations are detected by the olfactory receptors within the hose. This work is intended to convey to the reader the an up-to-date account of the vibrational theory of olfaction, both the historical iterations as well as the present iteration. This text is designed to give a chronological account of both theoretical and experimental studies on the topic, while providing context, comments and background where they were found to be needed.

  15. Conformational and vibrational reassessment of solid paracetamol

    Science.gov (United States)

    Amado, Ana M.; Azevedo, Celeste; Ribeiro-Claro, Paulo J. A.

    2017-08-01

    This work provides an answer to the urge for a more detailed and accurate knowledge of the vibrational spectrum of the widely used analgesic/antipyretic drug commonly known as paracetamol. A comprehensive spectroscopic analysis - including infrared, Raman, and inelastic neutron scattering (INS) - is combined with a computational approach which takes account for the effects of intermolecular interactions in the solid state. This allows a full reassessment of the vibrational assignments for Paracetamol, thus preventing the propagation of incorrect data analysis and misassignments already found in the literature. In particular, the vibrational modes involving the hydrogen-bonded Nsbnd H and Osbnd H groups are correctly reallocated to bands shifted by up to 300 cm- 1 relatively to previous assignments.

  16. Effects of Cutting Tool Parameters on Vibration

    Directory of Open Access Journals (Sweden)

    Ince Mehmet Alper

    2016-01-01

    Full Text Available This paper presents of the influence on vibration of Co28Cr6Mo medical alloy machined on a CNC lathe based on cutting parameters (rotational speed, feed rate, depth of cut and tool tip radius. The influences of cutting parameters have been presented in graphical form for understanding. To achieve the minimum vibration, the optimum values obtained for rpm, feed rate, depth of cut and tool tip radius were respectively, 318 rpm, 0.25 mm/rev, 0.9 mm and 0.8 mm. Maximum vibration has been revealed the values obtained for rpm, feed rate, depth of cut and tool tip radius were respectively, 636 rpm, 0.1 mm/rev, 0,5 mm and 0.8 mm.

  17. Control aid for xenon vibration in reactor

    International Nuclear Information System (INIS)

    Kanekawa, Takashi.

    1990-01-01

    In the present invention, the control operation for suppressing xenon vibrations in a reactor is aided for saving forecasting analysis and operator's skills. That is, parameters to be controlled for the suppression of xenon vibrations are power distribution, iodine distribution and xenon distribution. But what can be observed by operaters by the conventional fast overtone method is only the output distribution. In the present invention, the output level of the reactor core is always observed. Then, mathematical processings are conducted for the iodine distribution, the xenon distribution and the power distribution in the reactor core based on the histeresis of the parameters obtained by the measurement using physical constants and reactor design data. The xenon vibration control is aided by displaying the change with time of the distortion in axial direction. Accordingly, operators can always recognize the axial distortion of the power distribution, the iodine distribution and the xenon distribution. (I.S.)

  18. Vibration dynamics of single atomic nanocontacts

    International Nuclear Information System (INIS)

    Khater, A; Bourahla, B; Tigrine, R

    2007-01-01

    The motivation for this work is to introduce a model for an atomic nanocontact, whereby its mechanical properties can be analysed via the local spectra. The model system consists of two sets of triple parallel semi-infinite atomic chains joined by a single atom in between. We calculate the vibration spectra and the local densities of vibration states, in the harmonic approximation, for the irreducible set of sites that constitute the nanocontact domain. The nanocontact observables are numerically calculated for different cases of elastic hardening and softening, to investigate how the local dynamics can respond to changes in the microscopic environment on the domain. We have also calculated the phonon scattering and coherent conductance at the nanocontact, derived in a Landauer-Buettiker matrix approach. The analysis of the spectra, of the densities of vibration states, and of the phonon conductance, identifies characteristic features and demonstrates the central role of a core subset of sites in the nanocontact domain

  19. Vibration of liquid-filled thin shells

    International Nuclear Information System (INIS)

    Kalnins, A.

    1979-01-01

    This paper describes the analysis of free and forced vibration of a thin, axisymmetric shell, which contains some liquid. The axis of symmetry is vertical. Only such vibration is considered which can be produced by a horizontal movement of the base of shell. The objective of this paper is to examine the response of the coupled shell-liquid system for a frequency range lying between zero and the lowest natural sloshing frequency of the liquid. The mass of the liquid is modeled by a stationary and one or more sloshing masses. It is shown how the stationary mass can be incorporated in the vibration analysis of the shell and how to natural frequency of the coupled shell-liquid system can be obtained from a simple formula, if the lowest natural frequency of the shell, plus the stationary mass of the liquid, can be determined. A numerical example is given. (orig.)

  20. Desert ants learn vibration and magnetic landmarks.

    Directory of Open Access Journals (Sweden)

    Cornelia Buehlmann

    Full Text Available The desert ants Cataglyphis navigate not only by path integration but also by using visual and olfactory landmarks to pinpoint the nest entrance. Here we show that Cataglyphis noda can additionally use magnetic and vibrational landmarks as nest-defining cues. The magnetic field may typically provide directional rather than positional information, and vibrational signals so far have been shown to be involved in social behavior. Thus it remains questionable if magnetic and vibration landmarks are usually provided by the ants' habitat as nest-defining cues. However, our results point to the flexibility of the ants' navigational system, which even makes use of cues that are probably most often sensed in a different context.

  1. Vibration-damping structure for reactor building

    International Nuclear Information System (INIS)

    Kuno, Toshio; Iba, Chikara; Tanaka, Hideki; Kageyama, Mitsuru

    1998-01-01

    In a damping structure of a reactor building, an inner concrete body and a reactor container are connected by way of a vibration absorbing member. As the vibration absorbing member, springs or dampers are used. The inner concrete body and the reactor container each having weight and inherent frequency different from each other are opposed displaceably by way of the vibration absorbing member thereby enabling to reduce seismic input and reduce shearing force at least at leg portions. Accordingly, seismic loads are reduced to increase the grounding rate of the base thereby enabling to satisfy an allowable value. Therefore, it is not necessary to strengthen the inner concrete body and the reactor container excessively, the amount of reinforcing rods can be reduced, and the amount of a portion of the base buried to the ground can be reduced thereby enabling to constitute the reactor building easily. (N.H.)

  2. Vibration Based Sun Gear Damage Detection

    Science.gov (United States)

    Hood, Adrian; LaBerge, Kelsen; Lewicki, David; Pines, Darryll

    2013-01-01

    Seeded fault experiments were conducted on the planetary stage of an OH-58C helicopter transmission. Two vibration based methods are discussed that isolate the dynamics of the sun gear from that of the planet gears, bearings, input spiral bevel stage, and other components in and around the gearbox. Three damaged sun gears: two spalled and one cracked, serve as the focus of this current work. A non-sequential vibration separation algorithm was developed and the resulting signals analyzed. The second method uses only the time synchronously averaged data but takes advantage of the signal/source mapping required for vibration separation. Both algorithms were successful in identifying the spall damage. Sun gear damage was confirmed by the presence of sun mesh groups. The sun tooth crack condition was inconclusive.

  3. Fingers' vibration transmission and grip strength preservation performance of vibration reducing gloves.

    Science.gov (United States)

    Hamouda, K; Rakheja, S; Dewangan, K N; Marcotte, P

    2018-01-01

    The vibration isolation performances of vibration reducing (VR) gloves are invariably assessed in terms of power tools' handle vibration transmission to the palm of the hand using the method described in ISO 10819 (2013), while the nature of vibration transmitted to the fingers is ignored. Moreover, the VR gloves with relatively low stiffness viscoelastic materials affect the grip strength in an adverse manner. This study is aimed at performance assessments of 12 different VR gloves on the basis of handle vibration transmission to the palm and the fingers of the gloved hand, together with reduction in the grip strength. The gloves included 3 different air bladder, 3 gel, 3 hybrid, and 2 gel-foam gloves in addition to a leather glove. Two Velcro finger adapters, each instrumented with a three-axis accelerometer, were used to measure vibration responses of the index and middle fingers near the mid-phalanges. Vibration transmitted to the palm was measured using the standardized palm adapter. The vibration transmissibility responses of the VR gloves were measured in the laboratory using the instrumented cylindrical handle, also described in the standard, mounted on a vibration exciter. A total of 12 healthy male subjects participated in the study. The instrumented handle was also used to measure grip strength of the subjects with and without the VR gloves. The results of the study showed that the VR gloves, with only a few exceptions, attenuate handle vibration transmitted to the fingers only in the 10-200 Hz and amplify middle finger vibration at frequencies exceeding 200 Hz. Many of the gloves, however, provided considerable reduction in vibration transmitted to the palm, especially at higher frequencies. These suggest that the characteristics of vibration transmitted to fingers differ considerably from those at the palm. Four of the test gloves satisfied the screening criteria of the ISO 10819 (2013) based on the palm vibration alone, even though these caused

  4. Vibrational excitation in a hydrogen volume source

    International Nuclear Information System (INIS)

    Eenshuistra, P.J.

    1989-01-01

    In this thesis the complex of processes which determines the D - or H - density in a volume source, a hydrogen discharge, is studied. D - beams are of interest for driving the current of a fusion plasma in a TOKAMAK. Densities of vibrationally excited molecules, of H atoms, and of metastable hydrogen molecules were determined using Resonance-Enhanced MultiPhoton Ionization (REMPI). An experiment in which vibrationally highly excited molecules are formed by recombination of atoms in a cold metal surface, is described. The production and destruction of vibrationally excited molecules and atoms in the discharge is discussed. The vibrational distribution for 3≤ν≤5 (ν = vibrational quantumnumber) is strongly super-thermal. This effect is more apparent at higher discharge current and lower gas pressure. The analysis with a model based on rate equations, which molecules are predominantly produced by primary electron excitation of hydrogen molecules and deexcited upon one wall collision. The atom production is compatible with dissociation of molecules by primary electrons, dissociation of molecules on the filaments, and collisions between positive ions and electrons. The electrons are predominantly destroyed by recombination on the walls. Finally the production and destruction of H - in the discharge are discussed. The density of H - in the plasma, the electron density and temperature were determined. H - extraction was measured. The ratio of the extracted H - current and the H - density in the plasma gives an indication of the drift velocity of H - in the plasma. This velocity determines the emittance of the extracted beam. It was found that the H - velocity scales with the square root of the electron temperature. The measured H - densities are compatible with a qualitative model in which dissociative attachment of plasma electrons to vibrationally excited molecules is the most important process. (author). 136 refs.; 39 figs.; 10 tabs

  5. Diffusion of solid fuelon a vibrating grate

    DEFF Research Database (Denmark)

    Sabelström, Hanna Katarina

    of vibrations can be incorporated into a numerical model. The chosen model approach has been to separate the gas and solid phases into two independent models related to each other through the bed porosity. By treating the bed as a porous media and using Ergun's equation for the gas flow, the numerical work...... is simplified and the computational time shortened. The vibrations are affecting the transport and mixing of the fuel and incorporated into the model through the diffusion coefficient in the conservation equation of the solid phase. Experimental work has been carried out with the aim to study the behaviour...

  6. Forced vibrations of rotating circular cylindrical shells

    International Nuclear Information System (INIS)

    Igawa, Hirotaka; Maruyama, Yoshiyuki; Endo, Mitsuru

    1995-01-01

    Forced vibrations of rotating circular cylindrical shells are investigated. Basic equations, including the effect of initial stress due to rotation, are formulated by the finite-element method. The characteristic relations for finite elements are derived from the energy principle by considering the finite strain. The equations of motion can be separated into quasi-static and dynamic ones, i.e., the equations in the steady rotating state and those in the vibration state. Radial concentrated impulses are considered as the external dynamic force. The transient responses of circular cylindrical shells are numerically calculated under various boundary conditions and rotating speeds. (author)

  7. Noise and vibration in friction systems

    CERN Document Server

    Sergienko, Vladimir P

    2015-01-01

    The book analyzes the basic problems of oscillation processes and theoretical aspects of noise and vibration in friction systems. It presents generalized information available in literature data and results of the authors in vibroacoustics of friction joints, including car brakes and transmissions. The authors consider the main approaches to abatement of noise and vibration in non-stationary friction processes. Special attention is paid to materials science aspects, in particular to advanced composite materials used to improve the vibroacoustic characteristics of tribopairs The book is intended for researchers and technicians, students and post-graduates specializing in mechanical engineering, maintenance of machines and transport means, production certification, problems of friction and vibroacoustics.

  8. Rotor Vibration Reduction via Active Hybrid Bearings

    DEFF Research Database (Denmark)

    Nicoletti, Rodrigo; Santos, Ilmar

    2002-01-01

    The use of fluid power to reduce and control rotor vibration in rotating machines is investigated. An active hybrid bearing is studied, whose main objective is to reduce wear and vibration between rotating and stationary machinery parts. By injecting pressurised oil into the oil film, through...... orifices machined in the bearing pads, one can alter the machine dynamic characteristics, thus enhancing its operational range. A mathematical model of the rotor-bearing system, as well as of the hydraulic system, is presented. Numerical results of the system frequency response show good agreement...

  9. Active vibration control by robust control techniques

    International Nuclear Information System (INIS)

    Lohar, F.A.

    2001-01-01

    This paper studies active vibration control of multi-degree-of-freedom system. The control techniques considered are LTR, H/sup 2/ and H/sup infinite/. The results show that LTR controls the vibration but its respective settling time is higher than that of the other techniques. The control performance of H/sup infinite/ control is similar to that of H/sup 2/ control in the case of it weighting functions. However, H/sup infinite/ control is superior to H/sup 2/ control with respect to robustness, steady state error and settling time. (author)

  10. Vibration Energy Harvesting Potential for Turbomachinery Applications

    Directory of Open Access Journals (Sweden)

    Adrian STOICESCU

    2018-03-01

    Full Text Available The vibration energy harvesting process represents one of the research directions for increasing power efficiency of electric systems, increasing instrumentation nodes autonomy in hard to reach locations and decreasing total system mass by eliminating cables and higher-power adapters. Research based on the possibility of converting vibration energy into useful electric energy is used to evaluate the potential of its use on turbomachinery applications. Aspects such as the structure and characteristics of piezoelectric generators, harvesting networks, their setup and optimization, are considered. Finally, performance test results are shown using piezoelectric systems on a turbine engine.

  11. Vibrational spectroscopic study of fluticasone propionate

    Science.gov (United States)

    Ali, H. R. H.; Edwards, H. G. M.; Kendrick, J.; Scowen, I. J.

    2009-03-01

    Fluticasone propionate is a synthetic glucocorticoid with potent anti-inflammatory activity that has been used effectively in the treatment of chronic asthma. The present work reports a vibrational spectroscopic study of fluticasone propionate and gives proposed molecular assignments on the basis of ab initio calculations using BLYP density functional theory with a 6-31G* basis set and vibrational frequencies predicted within the quasi-harmonic approximation. Several spectral features and band intensities are explained. This study generated a library of information that can be employed to aid the process monitoring of fluticasone propionate.

  12. Vibrational spectroscopic study of terbutaline hemisulphate

    Science.gov (United States)

    Ali, H. R. H.; Edwards, H. G. M.; Kendrick, J.; Scowen, I. J.

    2009-05-01

    The Raman spectrum of terbutaline hemisulphate is reported for the first time, and molecular assignments are proposed on the basis of ab initio BLYP DFT calculations with a 6-31G* basis set and vibrational frequencies predicted within the quasi-harmonic approximation; these predictions compare favourably with the observed vibrational spectra. Comparison with previously published infrared data explains several spectral features. The results from this study provide data that can be used for the preparative process monitoring of terbutaline hemisulphate, an important β 2 agonist drug in various dosage forms and its interaction with excipients and other components.

  13. Destructive vibration test of a concrete structure

    International Nuclear Information System (INIS)

    Chen, C.K.; Czarnecki, R.M.; Scholl, R.E.

    1977-01-01

    Two identical full-scale 4-story reinforced concrete structures were built in 1965-1966 at the Nevada Test Site to investigate their dynamic response behavior to underground nuclear explosions. For eight years following their construction, the structures were the subject of a continuing program of vibration testing, and substantial data has been collected on the elastic response of these structures. In 1974 it was decided to conduct a high-amplitude vibration test that would cause the south structure (free of partitions) to deform beyond its elastic limit and cause major structural damage. Results of the 1974 testing program are summarized

  14. Optimal parameters uncoupling vibration modes of oscillators

    Science.gov (United States)

    Le, K. C.; Pieper, A.

    2017-07-01

    This paper proposes a novel optimization concept for an oscillator with two degrees of freedom. By using specially defined motion ratios, we control the action of springs to each degree of freedom of the oscillator. We aim at showing that, if the potential action of the springs in one period of vibration, used as the payoff function for the conservative oscillator, is maximized among all admissible parameters and motions satisfying Lagrange's equations, then the optimal motion ratios uncouple vibration modes. A similar result holds true for the dissipative oscillator having dampers. The application to optimal design of vehicle suspension is discussed.

  15. Design of Wind Turbine Vibration Monitoring System

    Directory of Open Access Journals (Sweden)

    Shoubin Wang

    2013-04-01

    Full Text Available In order to ensure safety of wind turbine operation and to reduce the occurrence of faults as well as to improve the reliability of wind turbine operation, a vibration monitoring for wind turbine is developed. In this paper, it analyses the enlargement of all the parts of the structure and the working mechanism, the research method of wind turbine operation vibration is introduced, with the focus being the use of the sensor principle. Finally the hardware design and software of this system is introduced and the main function of this system is described, which realizes condition monitoring of the work state of wind turbines.

  16. Lambda-matrices and vibrating systems

    CERN Document Server

    Lancaster, Peter; Stark, M; Kahane, J P

    1966-01-01

    Lambda-Matrices and Vibrating Systems presents aspects and solutions to problems concerned with linear vibrating systems with a finite degrees of freedom and the theory of matrices. The book discusses some parts of the theory of matrices that will account for the solutions of the problems. The text starts with an outline of matrix theory, and some theorems are proved. The Jordan canonical form is also applied to understand the structure of square matrices. Classical theorems are discussed further by applying the Jordan canonical form, the Rayleigh quotient, and simple matrix pencils with late

  17. Sensitivity improvement techniques for micromechanical vibrating accelerometers

    Directory of Open Access Journals (Sweden)

    Vtorushin Sergey

    2016-01-01

    Full Text Available The paper presents the problems of detecting a desired signal generated by micromechanical vibrating accelerometer. Three detection methods, namely frequency, amplitude and phase are considered in this paper. These methods are used in micromechanical vibrating accelerometers that incorporate a force sensitive element which transforms measured acceleration into the output signal. Investigations are carried out using the ANSYS finite element program and MATLAB/Simulink support package. Investigation results include the comparative analysis of the output signal characteristics obtained by the different detection methods.

  18. Vibrational Based Inspection Of A Steel Mast

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Rytter, A.

    1994-01-01

    The aim of this paper is to present the results from a research project concerning vibrational based inspection of a 20 meter high steel mast containing well defined damages. Introductory analyses dealing with among other things evaluation of potential damage indicators and determination of accep......The aim of this paper is to present the results from a research project concerning vibrational based inspection of a 20 meter high steel mast containing well defined damages. Introductory analyses dealing with among other things evaluation of potential damage indicators and determination...

  19. Localized Surface Plasmons in Vibrating Graphene Nanodisks

    DEFF Research Database (Denmark)

    Wang, Weihua; Li, Bo-Hong; Stassen, Erik

    2016-01-01

    in graphene disks have the additional benefit to be highly tunable via electrical stimulation. Mechanical vibrations create structural deformations in ways where the excitation of localized surface plasmons can be strongly modulated. We show that the spectral shift in such a scenario is determined...... by a complex interplay between the symmetry and shape of the modal vibrations and the plasmonic mode pattern. Tuning confined modes of light in graphene via acoustic excitations, paves new avenues in shaping the sensitivity of plasmonic detectors, and in the enhancement of the interaction with optical emitters...

  20. Fractional order absolute vibration suppression (AVS) controllers

    Science.gov (United States)

    Halevi, Yoram

    2017-04-01

    Absolute vibration suppression (AVS) is a control method for flexible structures. The first step is an accurate, infinite dimension, transfer function (TF), from actuation to measurement. This leads to the collocated, rate feedback AVS controller that in some cases completely eliminates the vibration. In case of the 1D wave equation, the TF consists of pure time delays and low order rational terms, and the AVS controller is rational. In all other cases, the TF and consequently the controller are fractional order in both the delays and the "rational parts". The paper considers stability, performance and actual implementation in such cases.

  1. Optical Measurement of Cable and String Vibration

    Directory of Open Access Journals (Sweden)

    Y. Achkire

    1998-01-01

    Full Text Available This paper describes a non contacting measurement technique for the transverse vibration of small cables and strings using an analog position sensing detector. On the one hand, the sensor is used to monitor the cable vibrations of a small scale mock-up of a cable structure in order to validate the nonlinear cable dynamics model. On the other hand, the optical sensor is used to evaluate the performance of an active tendon control algorithm with guaranteed stability properties. It is demonstrated experimentally, that a force feedback control law based on a collocated force sensor measuring the tension in the cable is feasible and provides active damping in the cable.

  2. Piping vibrations measured during FFTF startup

    International Nuclear Information System (INIS)

    Anderson, M.J.

    1981-03-01

    An extensive vibration survey was conducted on the Fast Flux Test Facility piping during the plant acceptance test program. The purpose was to verify that both mechanical and flow induced vibration amplitudes were of sufficiently low level so that pipe and pipe support integrity would not be compromised over the plant design lifetime. Excitation sources included main heat transport sodium pumps, reciprocating auxiliary system pumps, EM pumps, and flow oscillations. Pipe sizes varied from one-inch to twenty-eight-inches in diameter. This paper describes the test plan; the instrumentation and procedures utilized; and the test results

  3. Infrared spectroscopy of flavones and flavonols. Reexamination of the hydroxyl and carbonyl vibrations in relation to the interactions of flavonoids with membrane lipids

    Science.gov (United States)

    Baranović, Goran; Šegota, Suzana

    2018-03-01

    Detailed vibrational assignments for twelve flavonoids (seven flavones (flavone, 3- and 5-hydroxyflavone, chrysin, apigenin, fisetin and luteolin) and five flavonols (galangin, kaempferol, quercetin, morin and myricetin)) have been made based on own and reported experimental data and calculations at the B3LYP/6-31 + G(d,p) level of theory. All the molecules are treated in a uniform way by using the same set of redundancy-free set of internal coordinates. A generalized harmonic mode mixing is used to corroborate the vibrational characteristics of this important class of molecules. Each flavonoid molecule can be treated from the vibrational point of view as made of relatively weakly coupled chromone and phenyl part. It has been shown that the strongest band around 1600 cm- 1 need not be attributable to the Cdbnd O stretching. The way the vibrations of any of the hydroxyl groups are mixed with ring vibrations and vibrations of other neighboring hydroxyl groups is rather involved. This imposes severe limitations on any attempt to describe normal modes of a flavonol in terms of hydroxyl or carbonyl group vibrations. The role of water molecules in the appearance of flavonoid IR spectra is emphasized. Knowing for the great affinity of phosphate groups in lipids towards water, the immediate consequence is a reasonable assumption that flavonoid lipid interactions is mediated by water.

  4. Integrated predictive maintenance program vibration and lube oil analysis: Part I - history and the vibration program

    Energy Technology Data Exchange (ETDEWEB)

    Maxwell, H.

    1996-12-01

    This paper is the first of two papers which describe the Predictive Maintenance Program for rotating machines at the Palo Verde Nuclear Generating Station. The organization has recently been restructured and significant benefits have been realized by the interaction, or {open_quotes}synergy{close_quotes} between the Vibration Program and the Lube Oil Analysis Program. This paper starts with the oldest part of the program - the Vibration Program and discusses the evolution of the program to its current state. The {open_quotes}Vibration{close_quotes} view of the combined program is then presented.

  5. Heavy atom vibrational modes and low-energy vibrational autodetachment in nitromethane anions

    International Nuclear Information System (INIS)

    Thompson, Michael C.; Weber, J. Mathias; Baraban, Joshua H.; Matthews, Devin A.; Stanton, John F.

    2015-01-01

    We report infrared spectra of nitromethane anion, CH 3 NO 2 − , in the region 700–2150 cm −1 , obtained by Ar predissociation spectroscopy and electron detachment spectroscopy. The data are interpreted in the framework of second-order vibrational perturbation theory based on coupled-cluster electronic structure calculations. The modes in the spectroscopic region studied here are mainly based on vibrations involving the heavier atoms; this work complements earlier studies on nitromethane anion that focused on the CH stretching region of the spectrum. Electron detachment begins at photon energies far below the adiabatic electron affinity due to thermal population of excited vibrational states

  6. Wireless Inductive Power Device Suppresses Blade Vibrations

    Science.gov (United States)

    Morrison, Carlos R.; Provenza, Andrew J.; Choi, Benjamin B.; Bakhle, Milind A.; Min, James B.; Stefko, George L.; Duffy, Kirsten P.; Fougers, Alan J.

    2011-01-01

    Vibration in turbomachinery can cause blade failures and leads to the use of heavier, thicker blades that result in lower aerodynamic efficiency and increased noise. Metal and/or composite fatigue in the blades of jet engines has resulted in blade destruction and loss of lives. Techniques for suppressing low-frequency blade vibration, such as gtuned circuit resistive dissipation of vibratory energy, h or simply "passive damping," can require electronics incorporating coils of unwieldy dimensions and adding unwanted weight to the rotor. Other approaches, using vibration-dampening devices or damping material, could add undesirable weight to the blades or hub, making them less efficient. A wireless inductive power device (WIPD) was designed, fabricated, and developed for use in the NASA Glenn's "Dynamic Spin Rig" (DSR) facility. The DSR is used to simulate the functionality of turbomachinery. The relatively small and lightweight device [10 lb (approx.=4.5 kg)] replaces the existing venerable and bulky slip-ring. The goal is the eventual integration of this technology into actual turbomachinery such as jet engines or electric power generators, wherein the device will facilitate the suppression of potentially destructive vibrations in fan blades. This technology obviates slip rings, which require cooling and can prove unreliable or be problematic over time. The WIPD consists of two parts: a remote element, which is positioned on the rotor and provides up to 100 W of electrical power to thin, lightweight piezoelectric patches strategically placed on/in fan blades; and a stationary base unit that wirelessly communicates with the remote unit. The base unit supplies inductive power, and also acts as an input and output corridor for wireless measurement, and active control command to the remote unit. Efficient engine operation necessitates minimal disturbance to the gas flow across the turbine blades in any effort to moderate blade vibration. This innovation makes it

  7. Do Scaphoideus titanus (Hemiptera: Cicadellidae) nymphs use vibrational communication?

    Science.gov (United States)

    Chuche, Julien; Thiéry, Denis; Mazzoni, Valerio

    2011-07-01

    Small Auchenorrhyncha use substrate-borne vibrations to communicate. Although this behaviour is well known in adult leafhoppers, so far no studies have been published on nymphs. Here we checked the occurrence of vibrational communication in Scaphoideus titanus (Hemiptera: Cicadellidae) nymphs as a possible explanation of their aggregative distributions on host plants. We studied possible vibratory emissions of isolated and grouped nymphs, as well as their behavioural responses to vibration stimuli that simulated presence of conspecifics, to disturbance noise, white noise and predator spiders. None of our synthetic stimuli or pre-recorded substrate vibrations from nymphs elicited specific vibration responses and only those due to grooming or mechanical contacts of the insect with the leaf were recorded. Thus, S. titanus nymphs showed to not use species-specific vibrations neither for intra- nor interspecific communication and also did not produce alarm vibrations when facing potential predators. We conclude that their aggregative behaviour is independent from a vibrational communication.

  8. Alleviation of Buffet-Induced Vibration Using Piezoelectric Actuators

    National Research Council Canada - National Science Library

    Morgenstern, Shawn D

    2006-01-01

    .... The objective of this research was to determine the most critical natural modes of vibration for the F-16 ventral fin and design piezoelectric actuators capable of reducing buffet-induced ventral fin vibration...

  9. Evaluation methods of vibration stress of small bore piping

    Energy Technology Data Exchange (ETDEWEB)

    Hiramatsu, Miki; Sasaki, Toru [Institute of Nuclear Safety System Inc., Mihama, Fukui (Japan)

    2001-09-01

    Fatigue fracture by vibration stress is one of the main causes of troubles which occur at small bore piping in nuclear power plants. Therefore at the plants they manage small bore piping using a method in which their vibration accelerations are measured and the vibration stresses are calculated. In this work, vibration tests for two sets of mock-ups simulating actual piping in the plants by sinusoidal oscillation and by that obtained at an actual plant were carried out, and then an evaluation method was developed to obtain proper value of vibration stress from the measured data by the vibration tests. In comparison of the vibration stress obtained from the measured acceleration with that directly measured using strain gauges, it is confirmed that accurate vibration stress can be evaluated by a formula in which the real center of gravity of small bore piping and the acceleration of main (system) piping are considered. (author)

  10. Active vibration isolation of a rigidly mounted turbo pump

    NARCIS (Netherlands)

    Basten, T.G.H.; Doppenberg, E.J.J.

    2006-01-01

    Manufacturers of precision equipment are constantly aiming at increased accuracy. Elimination of disturbing vibrations is therefore getting more and more important. The technical limitations of passive isolation methods require alternative strategies for vibration reduction, such as active

  11. mediation: R package for causal mediation analysis

    OpenAIRE

    Tingley, Dustin; Yamamoto, Teppei; Hirose, Kentaro; Keele, Luke; Imai, Kosuke

    2012-01-01

    In this paper, we describe the R package mediation for conducting causal mediation analysis in applied empirical research. In many scientific disciplines, the goal of researchers is not only estimating causal effects of a treatment but also understanding the process in which the treatment causally affects the outcome. Causal mediation analysis is frequently used to assess potential causal mechanisms. The mediation package implements a comprehensive suite of statistical tools for conducting su...

  12. Micro dynamics in mediation

    OpenAIRE

    Boserup, Hans

    2014-01-01

    The author has identified a number of styles in mediation, which lead to different processes and different outcomes. Through discourse and conversation analysis he examines the micro dynamics in three of these, the postmodern styles: systemic, transformative and narrative mediation. The differences between the three mediation ideologies and practice is illustrated through role play scripts enacted in each style. Mediator and providers of mediation and trainers in mediation are encouraged to a...

  13. Low-frequency characteristics extension for vibration sensors

    Institute of Scientific and Technical Information of China (English)

    杨学山; 高峰; 候兴民

    2004-01-01

    Traditional magneto-electric vibration sensors and servo accelerometers have severe shortcomings when used to measure vibration where low frequency components predominate. A low frequency characteristic extension for velocity vibration sensors is presented in this paper. The passive circuit technology, active compensation technology and the closedcycle pole compensation technology are used to extend the measurable range and to improve low frequency characteristics of sensors. Thses three types of low frequency velocity vibration sensors have been developed and widely adopted in China.

  14. Spindle vibration and sound field measurement using optical vibrometry

    OpenAIRE

    Tatar, Kourosh

    2008-01-01

    Mechanical systems often produce a considerable amount of vibration and noise. To be able to obtain a complete picture of the dynamic behaviour of these systems, vibration and sound measurements are of significant importance. Optical metrology is well-suited for non-intrusive measurements on complex objects. The development and the use of remote non-contact vibration measurement methods for spindles are described and vibration measurements on thin- walled structures and sound field measuremen...

  15. Adjustable Nonlinear Springs to Improve Efficiency of Vibration Energy Harvesters

    OpenAIRE

    Boisseau, S.; Despesse, G.; Seddik, B. Ahmed

    2012-01-01

    Vibration Energy Harvesting is an emerging technology aimed at turning mechanical energy from vibrations into electricity to power microsystems of the future. Most of present vibration energy harvesters are based on a mass spring structure introducing a resonance phenomenon that allows to increase the output power compared to non-resonant systems, but limits the working frequency bandwidth. Therefore, they are not able to harvest energy when ambient vibrations' frequencies shift. To follow sh...

  16. Vibrational spectra for hydrogenated amorphous semiconductors

    International Nuclear Information System (INIS)

    Kamitakahara, W.A.; Bouchard, A.M.; Biswas, R.; Gompf, F.; Suck, J.B.

    1990-01-01

    Hydrogen vibration spectra have been measured by neutron scattering for several amorphous semiconductor materials, including a-Ge:H and a-SiC:H samples containing about 10 at. % H. The data for a-Ge:H are compared in detail with the results of realistic computer simulations

  17. Vibration of Elastic Functionally Graded Thick Rings

    Directory of Open Access Journals (Sweden)

    Guang-Hui Xu

    2017-01-01

    Full Text Available The free vibration behaviors of functionally graded rings were investigated theoretically. The material graded in the thickness direction according to the power law rule and the rings were assumed to be in plane stress and plane strain states. Based on the first-order shear deformation theory and the kinetic relation of von Kárman type, the frequency equation for free vibration of functionally graded ring was derived. The derived results were verified by those in literatures which reveals that the present theory can be appropriate to predict the free vibration characteristics for quite thick rings with the radius-to-thickness ratio from 60 down to 2.09. Comparison between the plane stress case and the plane strain case indicates a slight difference. Meanwhile, the effects of the structural dimensional parameters and the material inhomogeneous parameter are examined. It is interesting that the value of the logarithmic form of vibration frequency is inversely proportional to the logarithmic form of the radius-to-thickness ratio or the mean radius.

  18. Vibrational dynamics of ice in reverse micelles

    NARCIS (Netherlands)

    Dokter, A.M.; Petersen, C.; Woutersen, S.; Bakker, H.J.

    2008-01-01

    he ultrafast vibrational dynamics of HDO:D2O ice at 180 K in anionic reverse micelles is studied by midinfrared femtosecond pump-probe spectroscopy. Solutions containing reverse micelles are cooled to low temperatures by a fast-freezing procedure. The heating dynamics of the micellar solutions is

  19. Neutron reflectometry with ROG and mechanical vibrations

    International Nuclear Information System (INIS)

    Well, A.A. van.

    1991-11-01

    Specifications for the maximum level of vibrational amplitudes at the sample position of the IRI neutron reflectometer ROG are presented. The acceleration and displacement amplitudes in the reactor floor have been measured as a function of frequency. These measured values meet the ROG specifications. (author). 11 figs.; 1 tab

  20. Experimental study of acoustic vibration in BWRs

    International Nuclear Information System (INIS)

    Kumagai, Kosuke; Someya, Satoshi; Okamoto, Koji

    2009-01-01

    In recent years, the power uprate of Boiling Water Reactors have been conducted at several existing power plants as a way to improve plant economy. In one of the power uprated plants (117.8% uprates) in the United States, the steam dryer breakages due to fatigue fracture occurred. It is conceivable that the increased steam flow passing through the branches caused a self-induced vibration with the propagation of sound wave into the steam-dome. The resonance among the structure, flow and the pressure fluctuation resulted in the breakages. To understand the basic mechanism of the resonance, previous researches were done by a point measurement of the pressure and by a phase averaged measurement of the flow, while it was difficult to detect the interaction among them by the conventional method. In this study, Dynamic Particle Image Velocimetry (PIV) System was applied to investigate the effect of sound on natural convection and forced convection. Dynamic PIV system is the newest entrant to the field of fluid flow measurement. Its paramount advantage is the instantaneous global evaluation of conditions over plane extended across the whole velocity field. Also, to evaluate the coupling between the acoustic wave and structure (simulated as tuning fork vibrator in this experiment), in the resonance frequency of tuning fork vibrator, fluid behavior and the motion of tuning fork vibrator are measured simultaneously. (author)

  1. Fluid elastic vibration of nuclear fuel assemblies

    International Nuclear Information System (INIS)

    Kim, S. N.; Jung, S. Y.

    1998-01-01

    Since utilities and fuel venders have adopted the fuel design of high burn-up and improved thermal margin flow mixing vane, several PWR nuclear power plants have in recent years experienced fretting wear fuel rod failure due to flow induced vibration. Flow induced vibration can be resulted from fluidelastic instability, periodic shedding, turbulence-induced excitation, and acoustic resonance (1). Among these mechanisms found in the core of nuclear power plant, the governing mechanism that is fluidelastic instability, could be inferred from the analysis of fuel failure patterns. Therefore, to simulate the fuel failure in nuclear power plants, Tanaka's model (2) was chosen as most suitable one, which is well explaining the damage pattern, in particular it's second row damage characteristics. In the model, unsteady fluid dynamic forces acting on the vibrating cyclinders were included which consists of the inertia forces due to the added mass of fluid, damping forces of fluid in phase to the cylinder vibrating velocity, and stiffness forces proportional to cylinder displacements. However, the model did not account for radiation effect-spring forces deflection. So, the model was modified to account for the spring force relaxation due to radiation exposure. The stiffness of spring was fitted with experimental data. Finally the critical velocities were calculated with the modified spring force at beginning and end of cycle

  2. Smart paint sensor for monitoring structural vibrations

    International Nuclear Information System (INIS)

    Al-Saffar, Y; Baz, A; Aldraihem, O

    2012-01-01

    A class of smart paint sensors is proposed for monitoring the structural vibration of beams. The sensor is manufactured from an epoxy resin which is mixed with carbon black nano-particles to make it electrically conducting and sensitive to mechanical vibrations. A comprehensive theoretical and experimental investigation is presented to understand the underlying phenomena governing the operation of this class of paint sensors and evaluate its performance characteristics. A theoretical model is presented to model the electromechanical behavior of the sensor system using molecular theory. The model is integrated with an amplifier circuit in order to predict the current and voltage developed by the paint sensor when subjected to loading. Furthermore, the sensor/amplifier circuit models are coupled with a finite element model of a base beam to which the sensor is bonded. The resulting multi-field model is utilized to predict the behavior of both the sensor and the beam when subjected to a wide variety of vibration excitations. The predictions of the multi-field finite element model are validated experimentally and the behavior of the sensor is evaluated both in the time and the frequency domains. The performance of the sensor is compared with the performance of conventional strain gages to emphasize its potential and merits. The presented techniques are currently being extended to sensors that can monitor the vibration and structural power flow of two-dimensional structures. (paper)

  3. Vibrating crystals as possible neutron monochromators

    International Nuclear Information System (INIS)

    Stoica, A.D.; Popovici, M.

    1983-09-01

    The Bragg reflection of neutrons of vibratinq perfect crystals is considered. The additional possibilities offered by the Doppler effect for shaping neutron beams in the k-space are discussed. A simple model for computing the vibrating crystal reflectivity is proposed. (author)

  4. Toward yrast spectroscopy in soft vibrational nuclei

    International Nuclear Information System (INIS)

    Marumori, Toshio; Kuriyama, Atsushi; Sakata, Fumihiko.

    1979-10-01

    In a formally parallel way with that exciting progress has been recently achieved in understanding the yrast spectra of the rotational nuclei in terms of the quasi-particle motion in the rotating frame, an attempt to understand the yrast spectra of the vibrational nuclei in terms of the quasi-particle motion is proposed. The essential idea is to introduce the quasi-particle motion in a generalized vibrating frame, which can be regarded as a rotating frame in the gauge space of ''physical'' phonons where the number of the physical phonons plays the role of the angular momentum. On the basis of a simple fundamental principle called as the ''invariance principle of the Schroedinger equation'', which leads us to the ''maximal decoupling'' between the physical phonon and the intrinsic modes, it is shown that the vibrational frame as well as the physical-phonon-number operator represented by the quasi-particles can be self-consistently determined. A new scope toward the yrast spectroscopy of the vibrational nuclei in terms of the quasi-particle motion is discussed. (author)

  5. Measuring vibrations in fuel channels CNE

    International Nuclear Information System (INIS)

    Martín Ghiselli, A.; Fiori, J.; Sacchi, M.; Villabrille, G.

    2013-01-01

    This paper present a description of implementation and execution of vibration measurements made at the request of NUCLEOELECTRICA ARGENTINA S.A. on the ends of the reactor fuel channels of Embalse Nuclear Power Plant to explore possible differences between the dynamic behavior of empty fuel channel and with full charge of fuel elements inside. (author)

  6. Active Vibration Control of Hydrodynamic Journal Bearings

    Science.gov (United States)

    Tůma, J.; Šimek, J.; Škuta, J.; Los, J.; Zavadil, J.

    Rotor instability is one of the most serious problems of high-speed rotors supported by sliding bearings. With constantly increasing parameters, new machines problems with rotor instability are encountered more and more often. Even though there are many solutions based on passive improvement of the bearing geometry to enlarge the operational speed range of the journal bearing, the paper deals with a working prototype of a system for the active vibration control of journal bearings with the use of piezoactuators. The actively controlled journal bearing consists of a movable bushing, which is actuated by two piezoactuators. It is assumed that the journal vibration is measured by a pair of proximity probes. Force produced by piezoactuators and acting at the bushing is controlled according to error signals derived from the proximity probe output signals. The active vibration control was tested with the use of a test rig, which consists of a rotor supported by two controllable journal bearings and driven by an inductive motor up to 23,000 rpm. As it was proved by experiments the active vibration control extends considerably the range of the rotor operational speed.

  7. Lambda-matrices and vibrating systems

    CERN Document Server

    Lancaster, Peter

    2002-01-01

    Features aspects and solutions of problems of linear vibrating systems with a finite number of degrees of freedom. Starts with development of necessary tools in matrix theory, followed by numerical procedures for relevant matrix formulations and relevant theory of differential equations. Minimum of mathematical abstraction; assumes a familiarity with matrix theory, elementary calculus. 1966 edition.

  8. Internal Temperature Control For Vibration Testers

    Science.gov (United States)

    Dean, Richard J.

    1996-01-01

    Vibration test fixtures with internal thermal-transfer capabilities developed. Made of aluminum for rapid thermal transfer. Small size gives rapid response to changing temperatures, with better thermal control. Setup quicker and internal ducting facilitates access to parts being tested. In addition, internal flows smaller, so less energy consumed in maintaining desired temperature settings.

  9. Vibrational enhancement of total breakup cross sections

    International Nuclear Information System (INIS)

    Haftel, M.I.; Lim, T.K.

    1984-01-01

    This paper considers the role of multi-two-body bound states, namely vibrational excitations, on total three-body breakup cross-sections. Total cross-sections are usually easy to measure, and they play a fundamental role in chemical kinetics. (orig.)

  10. Vibrations of a pipe on elastic foundations

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    MARKOVA and D S LOLOV. Department of Technical Mechanics, Faculty of Hydro-technics, University of ... rotational springs at the length of the pipe. A new term appears in the equation of the transverse vibrations. This new term is opposed to the ...

  11. Vibration noise control in laser satellite communication

    Science.gov (United States)

    Saksonov, Avigdor; Shlomi, Arnon; Kopeika, Norman S.

    2001-08-01

    Laser satellite communication has become especially attractive in recent years. Because the laser beam width is narrow than in the RF or microwave range, the transmitted optical power may be significantly reduced. This leads to development of miniature communication systems with extremely low power consumption. On the other hand, the laser communication channel is very sensitive to vibrations of the optical platform. These vibrations cause angular noise in laser beam pointing, comparable to the laser beam width. As result, as significant portion of the optical power between transmitter and receiver is lost and the bit error rate is increased. Consequently, vibration noise control is a critical problem in laser satellite communication. The direction of the laser beam is corrected with a fast steering mirror (FSM). In this paper are presented two approaches for the FSM control. One is the feedback control that uses an LQG algorithm. The second is the direct feed- forward control when vibration noise is measured by three orthogonal accelerometers and drives directly the F SM. The performances of each approach are evaluated using MATLAB simulations.

  12. Strain and Vibration in Mesenchymal Stem Cells

    Directory of Open Access Journals (Sweden)

    Brooke McClarren

    2018-01-01

    Full Text Available Mesenchymal stem cells (MSCs are multipotent cells capable of differentiating into any mesenchymal tissue, including bone, cartilage, muscle, and fat. MSC differentiation can be influenced by a variety of stimuli, including environmental and mechanical stimulation, scaffold physical properties, or applied loads. Numerous studies have evaluated the effects of vibration or cyclic tensile strain on MSCs towards developing a mechanically based method of differentiation, but there is no consensus between studies and each investigation uses different culture conditions, which also influence MSC fate. Here we present an overview of the response of MSCs to vibration and cyclic tension, focusing on the effect of various culture conditions and strain or vibration parameters. Our review reveals that scaffold type (e.g., natural versus synthetic; 2D versus 3D can influence cell response to vibration and strain to the same degree as loading parameters. Hence, in the efforts to use mechanical loading as a reliable method to differentiate cells, scaffold selection is as important as method of loading.

  13. Friction brake cushions acceleration and vibration loads

    Science.gov (United States)

    Fraser, G. F.; Zawadski, G. Z.

    1966-01-01

    Friction brake cushions an object in a vehicle from axially applied vibration and steady-state acceleration forces. The brake incorporates a doubly tapered piston that applies a controlled radial force to friction brake segments bearing against the walls of a cylinder.

  14. On the particle-vibration multiplets

    International Nuclear Information System (INIS)

    Khodel, V.A.; Platonov, A.P.; Saperstein, E.E.

    1980-01-01

    The particle-vibration multiplet spectra in the lead region are calculated in the framework of the self-consistent theory of finite Fermi systems. The calculated results are compared with the experimental data and with the results of other authors. (author)

  15. Laserlike Vibrational Instability in Rectifying Molecular Conductors

    DEFF Research Database (Denmark)

    Lu, Jing Tao; Hedegård, Per; Brandbyge, Mads

    2011-01-01

    We study the damping of molecular vibrations due to electron-hole pair excitations in donor-acceptor (D-A) type molecular rectifiers. At finite voltage additional nonequilibrium electron-hole pair excitations involving both electrodes become possible, and contribute to the stimulated emission....... We investigate the effect in realistic molecular rectifier structures using first-principles calculations....

  16. Damage Detection by Laser Vibration Measurement

    Directory of Open Access Journals (Sweden)

    Elena Daniela Birdeanu

    2008-10-01

    Full Text Available The technique based on the vibration analysis by scanning laser Doppler vibrometer is one of the most promising, allowing to extract also small defect and to directly correlate it to local dynamic stiffness and structural integrity. In fact, the measurement capabilities of vibrometers, such as sensitivity, accuracy and reduced intrusively, allow having a very powerful instrument in diagnostic.

  17. Optimal control of vibrational transitions of HCl

    Indian Academy of Sciences (India)

    Control of fundamental and overtone transitions of a vibration are studied for the diatomic molecule, HCl. Specifically, the results of the effect of variation of the penalty factor on the physical attributes of the system (i.e., probabilities) and pulse (i.e., amplitudes) considering three different pulse durations for each value of the ...

  18. Intermodal resonance of vibrating suspended cables

    NARCIS (Netherlands)

    Rienstra, S.W.

    2010-01-01

    The weakly nonlinear free vibrations of a single suspended cable, or a coupled system of suspended cables, may be classified as gravity modes (no tension variations to leading order) and elasto-gravity modes (tension and vertical displacement equally important). It was found earlier [12] that the

  19. Modelling nuclear fuel vibrations in horizontal CANDU reactors

    International Nuclear Information System (INIS)

    Jagannath, D.V.; Oldaker, I.E.

    1976-01-01

    Flow-induced fuel vibrations in the pressure tubes of CANDU reactors are of vital interest to designers because fretting damage may result. Computer simulation is being used to study how bundles vibrate and to identify bundle design features which will reduce vibration and hence fretting. (author)

  20. Mitigating ground vibration by periodic inclusions and surface structures

    DEFF Research Database (Denmark)

    Andersen, Lars Vabbersgaard; Bucinskas, Paulius; Persson, Peter

    2016-01-01

    Ground vibration from traffic is a source of nuisance in urbanized areas. Trenches and wave barriers can provide mitigation of vibrations, but single barriers need to have a large depth to be effective-especially in the low-frequency range relevant to traffic-induced vibration. Alternatively...

  1. DOE/ANL/HTRI heat exchanger tube vibration data bank

    Energy Technology Data Exchange (ETDEWEB)

    Halle, H.; Chenoweth, J.M.; Wambsganss, M.W.

    1981-01-01

    This addendum to the DOE/ANL/HTRI Heat Exchanger Tube Vibration Data Bank includes 16 new case histories of field experiences. The cases include several exchangers that did not experience vibration problems and several for which acoustic vibration was reported.

  2. Predicting footbridge vibrations using a probability-based approach

    DEFF Research Database (Denmark)

    Pedersen, Lars; Frier, Christian

    2017-01-01

    Vibrations in footbridges may be problematic as excessive vibrations may occur as a result of actions of pedestrians. Design-stage predictions of levels of footbridge vibration to the action of a pedestrian are useful and have been employed for many years based on a deterministic approach to mode...

  3. Whole body vibration improves attention and motor performance in ...

    African Journals Online (AJOL)

    Background: Whole body vibration (WBV) is a form of physical stimulation via mechanical vibrations transmitted to a subject. It is assumed that WBV induces sensory stimulation in cortical brain regions through the activation of skin and muscle receptors responding to the vibration. The effects of WBV on muscle strength are ...

  4. Numerical analysis using state space method for vibration control of ...

    African Journals Online (AJOL)

    In passenger cars the vibrations developed at the ground are transmitted to the passengers through seats. Due to vibrations discomfort is experienced by the passengers. Dampers are being successfully utilized to reduce the vibrations in civil engineering structures. Few dampers are used in passenger cars as well.

  5. A novel technique for active vibration control, based on optimal

    Indian Academy of Sciences (India)

    In the last few decades, researchers have proposed many control techniques to suppress unwanted vibrations in a structure. In this work, a novel and simple technique is proposed for the active vibration control. In this technique, an optimal tracking control is employed to suppress vibrations in a structure by simultaneously ...

  6. Purification of drilling fluids by vibration-settling tanks

    Energy Technology Data Exchange (ETDEWEB)

    Bulatov, A.I.; Prokopov, L.I.; Proselkov, Yu.M.; Reznichenko, I.N.; Skvortsov, D.S.; Volkov, A.P.

    1982-01-01

    Results are presented of studies done by the authors of a prototype of a new tool for cleaning a drilling fluid, a vibration settling tank. It is indicated that the vibration settling tank has many advantages over the most advanced vibration screens VS-1. This makes it possible to recommend development and broad industrial testing of this apparatus.

  7. Experimental Study on Piezoelectric Energy Harvesting from Vortex-Induced Vibrations and Wake-Induced Vibrations

    Directory of Open Access Journals (Sweden)

    Min Zhang

    2016-01-01

    Full Text Available A rigid circular cylinder with two piezoelectric beams attached on has been tested through vortex-induced vibrations (VIV and wake-induced vibrations (WIV by installing a big cylinder fixed upstream, in order to study the influence of the different flow-induced vibrations (FIV types. The VIV test shows that the output voltage increases with the increases of load resistance; an optimal load resistance exists for the maximum output power. The WIV test shows that the vibration of the small cylinder is controlled by the vortex frequency of the large one. There is an optimal gap of the cylinders that can obtain the maximum output voltage and power. For a same energy harvesting device, WIV has higher power generation capacity; then the piezoelectric output characteristics can be effectively improved.

  8. Data of piezoelectric vibration energy harvesting of a bridge undergoing vibration testing and train passage

    Directory of Open Access Journals (Sweden)

    Paul Cahill

    2018-04-01

    Full Text Available The data presented in this article is in relation to the research article “Vibration energy harvesting based monitoring of an operational bridge undergoing forced vibration and train passage” Cahill et al. (2018 [1]. The article provides data on the full-scale bridge testing using piezoelectric vibration energy harvesters on Pershagen Bridge, Sweden. The bridge is actively excited via a swept sinusoidal input. During the testing, the bridge remains operational and train passages continue. The test recordings include the voltage responses obtained from the vibration energy harvesters during these tests and train passages. The original dataset is made available to encourage the use of energy harvesting for Structural Health Monitoring.

  9. Simulation of fuel rods vibration in power reactors by vibration of tape coated with cadmium

    International Nuclear Information System (INIS)

    Holland, L.

    1982-01-01

    The circulation of cooling water in light water power reactor makes a vibration in internal components. The monitoring of those vibrations is necessary aiming to the safety use of reactors. Aiming at study those vibrations a neutron absorber, type vibratory tape was introduced in the core of a research reactor type Pulstar, operating at 80 W of power. The induced power variations were measured with an ionization chamber put besides the reactor core. The detector signal was recorded and analysed in a PDP-11 computer. The analysis of the results show that the power density of the detector signal, and thus, the power reactor, increase in the O-25 Hz range with an increase in the pulse height vibration. (E.G.) [pt

  10. Vibration Analysis of a Residential Building

    Directory of Open Access Journals (Sweden)

    Sampaio Regina Augusta

    2015-01-01

    Full Text Available The aim of this paper is to present the results of a study regarding vibration problems in a 17 storey residential building during pile driving in its vicinity. The structural design of the building was checked according to the Brazilian standards NBR6118 and NBR6123, and using commercial finite element software. An experimental analysis was also carried out using low frequency piezo-accelerometers attached to the building structure. Structure vibrations were recorded under ambient conditions. Four monitoring tests were performed on different days. The objective of the first monitoring test was an experimental modal analysis. To obtain de modal parameters, data was processed in the commercial software ARTEMIS employing two methods: the Stochastic Subspace Identification and the Frequency Domain Decomposition. Human comfort was investigated considering the International Standard ISO 2631. The Portuguese standard, NP2074, was also used as a reference, since it aims to limit the adverse effects of vibrations in structures caused by pile driving in the vicinity of the structure. The carried out experimental tests have shown that, according to ISO2301, the measure vibration levels are above the acceptance limits. However, velocity peaks are below the limits established by NP2074. It was concluded that, although the structure has adequate capacity to resist internal forces according to normative criteria, it has low horizontal stiffness, which could be verified by observing the vibration frequencies and mode shapes obtained with the finite element models, and its similarity with the experimental results. Thus, the analyses indicate the occurrence of discomfort by the residents.

  11. Development of S-wave portable vibrator; S ha potable vibrator shingen no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Kaida, Y; Matsubara, Y [OYO Corp., Tokyo (Japan); Nijhof, V; Brouwer, J

    1996-05-01

    An S-wave portable vibrator to serve as a seismic source has been developed for the purpose of applying the shallow-layer reflection method to the study of the soil ground. The author, et al., who previously developed a P-wave portable vibrator has now developed an S-wave version, considering the advantage of the S-wave over the P-wave in that, for example, the S-wave velocity may be directly compared with the N-value representing ground strength and that the S-wave travels more slowly than the P-wave through sticky soil promising a higher-resolution exploration. The experimentally constructed S-wave vibrator consists of a conventional P-wave vibrator and an L-type wooden base plate combined therewith. Serving as the monitor for vibration is a conventional accelerometer without any modification. The applicability test was carried out at a location where a plank hammering test was once conducted for reflection aided exploration, and the result was compared with that of the plank hammering test. As the result, it was found that after some preliminary treatment the results of the two tests were roughly the same but that both reflected waves were a little sharper in the S-wave vibrator test than in the plank hammering test. 4 refs., 9 figs., 1 tab.

  12. The influence of flywheel micro vibration on space camera and vibration suppression

    Science.gov (United States)

    Li, Lin; Tan, Luyang; Kong, Lin; Wang, Dong; Yang, Hongbo

    2018-02-01

    Studied the impact of flywheel micro vibration on a high resolution optical satellite that space-borne integrated. By testing the flywheel micro vibration with six-component test bench, the flywheel disturbance data is acquired. The finite element model of the satellite was established and the unit force/torque were applied at the flywheel mounting position to obtain the micro vibration data of the camera. Integrated analysis of the data of the two parts showed that the influence of flywheel micro vibration on the camera is mainly concentrated around 60-80 Hz and 170-230 Hz, the largest angular displacement of the secondary mirror along the optical axis direction is 0.04″ and the maximum angular displacement vertical to optical axis is 0.032″. After the design and installation of vibration isolator, the maximum angular displacement of the secondary mirror is 0.011″, the decay rate of root mean square value of the angular displacement is more than 50% and the maximum is 96.78%. The whole satellite was suspended to simulate the boundary condition on orbit; the imaging experiment results show that the image motion caused by the flywheel micro vibrationis less than 0.1 pixel after installing the vibration isolator.

  13. VIBRATION SENSORS AND MICROELECTROMECHANICAL SYSTEM FOR MOBILE DEVICES SUCH AS ANALOGS, FOR EVALUATION OF VIBRATION OF ROTARY MACHINES

    Directory of Open Access Journals (Sweden)

    2016-01-01

    Full Text Available The paper carried out a comparison of vibration sensors used to measure the vibration condition units with gas turbine engines, with motion sensors, microelectromechanical systems used in modern mobile devices (for example, devices on the platform "Android". It provides opinions on the possibility of assessment of vibration, using sensors of mobile devices.

  14. EVALUATION AND MEASUREMENT OF HAND-TRANSMITTED VIBRATIONS

    Directory of Open Access Journals (Sweden)

    Iveta MARKOVÁ

    2017-12-01

    Full Text Available The goal of this work is the effect of vibrations on selected professionals through questionnaire survey and implementation of experimental vibration measurements on a hand of employee. The observation of vibration effects was chosen in a company, where products are being shaped with pneumatic instruments and there is a risk of an exposure of vibrations on the employees. In experimental part are described and evaluated questionnaire surveys conducted on selected risk factors. The reason is the realization of work with vibrating tools for a longer time, where some parts do wear-out and therefore there is a higher exposure to oscillation.

  15. Vertical vibration and shape oscillation of acoustically levitated water drops

    International Nuclear Information System (INIS)

    Geng, D. L.; Xie, W. J.; Yan, N.; Wei, B.

    2014-01-01

    We present the vertical harmonic vibration of levitated water drops within ultrasound field. The restoring force to maintain such a vibration mode is provided by the resultant force of acoustic radiation force and drop gravity. Experiments reveal that the vibration frequency increases with the aspect ratio for drops with the same volume, which agrees with the theoretical prediction for those cases of nearly equiaxed drops. During the vertical vibration, the floating drops undergo the second order shape oscillation. The shape oscillation frequency is determined to be twice the vibration frequency.

  16. Vertical vibration and shape oscillation of acoustically levitated water drops

    Energy Technology Data Exchange (ETDEWEB)

    Geng, D. L.; Xie, W. J.; Yan, N.; Wei, B., E-mail: bbwei@nwpu.edu.cn [Department of Applied Physics, Northwestern Polytechnical University, Xi' an 710072 (China)

    2014-09-08

    We present the vertical harmonic vibration of levitated water drops within ultrasound field. The restoring force to maintain such a vibration mode is provided by the resultant force of acoustic radiation force and drop gravity. Experiments reveal that the vibration frequency increases with the aspect ratio for drops with the same volume, which agrees with the theoretical prediction for those cases of nearly equiaxed drops. During the vertical vibration, the floating drops undergo the second order shape oscillation. The shape oscillation frequency is determined to be twice the vibration frequency.

  17. Methods of performing downhole operations using orbital vibrator energy sources

    Science.gov (United States)

    Cole, Jack H.; Weinberg, David M.; Wilson, Dennis R.

    2004-02-17

    Methods of performing down hole operations in a wellbore. A vibrational source is positioned within a tubular member such that an annulus is formed between the vibrational source and an interior surface of the tubular member. A fluid medium, such as high bulk modulus drilling mud, is disposed within the annulus. The vibrational source forms a fluid coupling with the tubular member through the fluid medium to transfer vibrational energy to the tubular member. The vibrational energy may be used, for example, to free a stuck tubular, consolidate a cement slurry and/or detect voids within a cement slurry prior to the curing thereof.

  18. Analysis of different vibration patterns to guide blind people.

    Science.gov (United States)

    Durá-Gil, Juan V; Bazuelo-Ruiz, Bruno; Moro-Pérez, David; Mollà-Domenech, Fernando

    2017-01-01

    The literature indicates the best vibration positions and frequencies on the human body where tactile information is transmitted. However, there is a lack of knowledge about how to combine tactile stimuli for navigation. The aim of this study is to compare different vibration patterns outputted to blind people and to determine the most intuitive vibration patterns to indicate direction for navigation purposes through a tactile belt. The vibration patterns that stimulate the front side of the waist are preferred for indicating direction. Vibration patterns applied on the back side of the waist could be suitable for sending messages such as stop.

  19. Analysis of different vibration patterns to guide blind people

    Directory of Open Access Journals (Sweden)

    Juan V. Durá-Gil

    2017-03-01

    Full Text Available The literature indicates the best vibration positions and frequencies on the human body where tactile information is transmitted. However, there is a lack of knowledge about how to combine tactile stimuli for navigation. The aim of this study is to compare different vibration patterns outputted to blind people and to determine the most intuitive vibration patterns to indicate direction for navigation purposes through a tactile belt. The vibration patterns that stimulate the front side of the waist are preferred for indicating direction. Vibration patterns applied on the back side of the waist could be suitable for sending messages such as stop.

  20. Apparatus and method for vibrating a casing string during cementing

    International Nuclear Information System (INIS)

    Rankin, R.E.; Rankin, K.T.

    1992-01-01

    This patent describes a method of cementing a string of casing in a well. It comprises: securing a vibrating device into the string of casing near the lower end of the string of casing; lowering the string of casing into the well to the desired depth; pumping a cement slurry down the string of casing; causing a portion of the cement slurry being pumped down the string of casing to vibrate the vibrating device; and wherein the vibrating device is secured in the string of casing by cementing the vibrating device within a sub, then securing the sub into the string of casing prior to lowering the string of casing into the well

  1. Reactor internals vibration monitoring by neutron noise methods in PWRs

    International Nuclear Information System (INIS)

    Pazsit, I.; Por, G.; Lux, I.

    1983-01-01

    Certain elements of PWR cores such as control/fuel rods or cassettes, or other parts of reactor internals, often represent a vibration problem. Early analyses at operating PWR plant revealed that these vibrations can be detected by in-core neutron detectors, opening up the possibility of vibration monitoring and diagnostics by noise methods. Theoretical methods of calculating vibration induced neutron noise and its application to vibration diagnostics are summarized. Experiments to check theoretical conclusions are under way at the Central Research Institute for Physics, Budapest. (author)

  2. Vibrational mechanics nonlinear dynamic effects, general approach, applications

    CERN Document Server

    Blekhman, Iliya I

    2000-01-01

    This important book deals with vibrational mechanics - the new, intensively developing section of nonlinear dynamics and the theory of nonlinear oscillations. It offers a general approach to the study of the effect of vibration on nonlinear mechanical systems.The book presents the mathematical apparatus of vibrational mechanics which is used to describe such nonlinear effects as the disappearance and appearance under vibration of stable positions of equilibrium and motions (i.e. attractors), the change of the rheological properties of the media, self-synchronization, self-balancing, the vibrat

  3. The photodissociation and reaction dynamics of vibrationally excited molecules

    Energy Technology Data Exchange (ETDEWEB)

    Crim, F.F. [Univ. of Wisconsin, Madison (United States)

    1993-12-01

    This research determines the nature of highly vibrationally excited molecules, their unimolecular reactions, and their photodissociation dynamics. The goal is to characterize vibrationally excited molecules and to exploit that understanding to discover and control their chemical pathways. Most recently the author has used a combination of vibrational overtone excitation and laser induced fluorescence both to characterize vibrationally excited molecules and to study their photodissociation dynamics. The author has also begun laser induced grating spectroscopy experiments designed to obtain the electronic absorption spectra of highly vibrationally excited molecules.

  4. Catalytic synthesis of ammonia using vibrationally excited nitrogen

    DEFF Research Database (Denmark)

    Henriksen, Niels Engholm; Billing, Gert D.; Hansen, Flemming Yssing

    1992-01-01

    In a previous study we have considered the catalytic synthesis of ammonia in the presence of vibrationally excited nitrogen. The distribution over vibrational states was assumed to be maintained during the reaction, and it was shown that the yield of ammonia increased considerably compared...... to that from conventional synthesis. In the present study the nitrogen molecules are only excited at the inlet of a plug flow reactor, and the importance of vibrational relaxation is investigated. We show that vibrational excitation can give an enhanced yield of ammonia also in the situation where vibrational...

  5. Anti-vibration bars for nuclear steam generators

    International Nuclear Information System (INIS)

    Gowda, B.V.; Wilson, R.M.; Wepfer, R.M.

    1986-01-01

    A method of installing tubular anti-vibration bars into a tube bundle of a steam generator wherein the tube bundle comprises rows of tubes, with the anti-vibration bars received between adjacent rows of the tube bundle for stabilizing the tubes against vibration. The anti-vibration bars are first inserted between adjacent rows of the tube bundle and a pressurized fluid is then introduced into the anti-vibration bars which are thus expanded into contact with the tubes of the adjacent rows for support

  6. Response of APS storage ring basemat to ambient vibration

    International Nuclear Information System (INIS)

    Jendrzejczyk, J.A.; Wambsganss, M.W.; Smith, R.K.

    1992-08-01

    The storage ring of the Advanced Photon Source (APS) facility at Argonne is very sensitive to vibration. Large vibration amplitudes would result in degraded machine performance. Because the storage ring assembly is supported on the storage ring basemat, the dynamics of the basemat are critical to successful operation. Before construction began, a survey of site ground vibration indicated that the site was acceptable from a vibration standpoint. When construction of the linear accelerator (Linac) floor slab and shielding walls was completed, dynamic-response measurements were conducted. The slab/wall system showed attenuation of soilborne vibrations in the horizontal directions, but an amplification (approximately a factor of 1.5) of vertical vibration at a frequency of 7.7 Hz. Vibration response of the slab/wall system at all other frequencies showed attenuation of soilborne vibrations. Dynamic-response measurements were also conducted on an incomplete section of the storage ring basemat. Although this section was not prototypical, results were similar to those of the Linac floor in the horizontal direction, showing large damping and attenuation of horizontal soilborne vibrations. While the basemat followed the soil vibration in the vertical direction, no large amplification was observed. However, measured vertical amplitudes on the basemat were a function of location, indicating a modal response. A series of vibration response measurements was conducted on a completed section of the storage ring basemat/tunnel adjacent and to the west of the Early Assembly Area (EAA) on May 21, 1992, and is the subject of this report

  7. The Health Effects and Keep Down of Whole Body Vibration

    Directory of Open Access Journals (Sweden)

    Funda Sevencan

    2014-04-01

    Full Text Available Vibration was defined that oscillation of the body according to the reference point. The tools that are used in industry and are the source of vibration cause diseases. For this reason, the vibration has been one of the factors that affect the health and of the most widely researched in the field of ergonomics. The perceived intensity and health effects of vibration depend on the vibration frequency, intensity, direction, acceleration, duration of exposure, vibration affects the region, age, gender, posture, distance from the source person, activity, time of day and the person\\s overall health condition. The one of the most common health effects of whole body vibration is impact on musculoskeletal system. In many studies, indicated that whole-body vibration effect waist, back, shoulder and neck especially. There were varied studies that hormone levels were not changed as well there were varied studies that hormone levels were increased or decreased. There were varied studies about the digestive and circulatory system. In these studies, digestive system complaints, peptic ulcer, gastritis, varicose veins and hemorrhoids were determined frequently. For protection the health effect of vibration, Directives of the European Commission, Turkish Standards, Assessment and Management of Environmental Noise and Vibration Regulations were published. For the control of vibration are need technical and medical measures and education [TAF Prev Med Bull 2014; 13(2.000: 177-186

  8. EFFECTOF ISOLATION WALL USING SCRAP TIRE ON GROUND VIBRATION REDUCTION

    Science.gov (United States)

    Kashimoto, Takahiko; Kashimoto, Yusuke; Hayakawa, Kiyoshi; Matsui, Tamotsu; Fujimoto, Hiroaki

    Some countermeasure methods against the environmental ground vibration caused by some traffic vibrations have been proposed so far. The authors have developed a new type ground vibration isolation wall using scrap tire, and evaluated its effectiveness on the ground vibration reduction by full scale field tests. In this paper, the authors discussed and examined the effectiveness of the developed countermeasure method by two field tests. The one concerns on the effect of scrap tire as soft material of vibration isolation wall, and the other on the effect of the developed countermeasure method practically applied in a residential area close to monorail traffic. As the results, it was elucidated that the ground vibration of 2-3 dB was reduced in case of two times volume of the soft material, the conversion ratio of the vibration energy of the soft material to the kinetic energy was higher than that of the core material of PHC pile, the vibration acceleration of 0.19 - 1.26 gal was reduced by the developed countermeasure method in case of the monorail traffic, and the vibration reduction measured behind the isolation wall agreed well with the proposed theoretical value, together with confirming the effectiveness of the ground vibration isolation wall using scrap tire as the countermeasure method against the environmental ground vibration.

  9. Hand-Arm vibration assessment among tiller operator

    Directory of Open Access Journals (Sweden)

    P. Nassiri

    2013-08-01

    Result: Results of the present study indicated that in all measured situations, exposure to hand arm vibration was higher than the standard limit suggested by Iranian occupational health committee and there was risk of vibration-induced disorders. The maximum exposure to vibration is in plowing ground. Exposure to hand arm vibration in three modes of plowing, transmission and natural, were respectively 16.95, 14.16 and 8.65 meters per second squared. Additionally, in all situations, vibration exposure was highest in the X-axis in comparison with Z- and Y-axes. .Conclusion: This study emphasizes on the need to provide intervention and controlling and managing strategies in order to eliminate or reduce vibration transmitted from tiller to operators hand and arm and also prevent to serious problems including neurovascular disorders, discomfort and white finger syndrome. Meanwhile, more studies are necessary to identify the sources of vibration on different models of tiller.

  10. Smart Sensor for Analyzing Train Vibration in WCR Zone

    Directory of Open Access Journals (Sweden)

    Alka DUBEY

    2009-09-01

    Full Text Available In the present paper a smart vibration sensor is developed for railway electric engine WAP-7. Which is a self-sensation device equipped with recording and wireless communication interface. One programmed microcontroller 89C52 is used, which record vibration of trains with real time into memory. There is certain limit of vibrations, which is acceptable by track. Beyond this limit track can be damaged and may result major casualty. Smart sensor indicate the level of current vibration with its ideal value for prevention of excessive vibration it starts buzz ring. The work is highly applicable to the high speed trains. The high level vibration cause serious accidents due to the vibration.

  11. Application of system concept in vibration and noise reduction

    Directory of Open Access Journals (Sweden)

    SHENG Meiping

    2017-08-01

    Full Text Available Although certain vibration and noise control technologies are maturing, such as vibration absorption, vibration isolation, sound absorption and sound insulation, and new methods for specific frequency bands or special environments have been proposed unceasingly, there is still no guarantee that practical effective vibration and noise reduction can be obtained. An important constraint for vibration and noise reduction is the lack of a system concept, and the integrity and relevance of such practical systems as ship structure have not obtained enough attention. We have tried to use the system engineering theory in guiding vibration and noise reduction, and have already achieved certain effects. Based on the system concept, the noise control of a petroleum pipeline production workshop has been completed satisfactorily, and the abnormal noise source identification of an airplane has been accomplished successfully. We want to share our experience and suggestions to promote the popularization of the system engineering theory in vibration and noise control.

  12. Dependence of steam generator vibrations on feedwater pressure

    International Nuclear Information System (INIS)

    Sadilek, J.

    1989-01-01

    Vibration sensors are attached to the bottom of the steam generator jacket between the input and output primary circuit collectors. The effective vibration value is recorded daily. Several times higher vibrations were observed at irregular intervals; their causes were sought, and the relation between the steam generator vibrations measured at the bottom of its vessel and the feedwater pressure was established. The source of the vibrations was found to be in the feedwater tract of the steam generator. The feedwater tract is described and its hydraulic characteristics are given. Vibrations were measured on the S02 valve. It is concluded that vibrations can be eliminated by reducing the water pressure before the control valves and by replacing the control valves with ones with more suitable control characteristics. (E.J.). 3 figs., 1 tab., 3 refs

  13. 10th International Conference on Vibration Problems

    CERN Document Server

    Horáček, Jaromír; Okrouhlík, Miloslav; Marvalová, Bohdana; Verhulst, Ferdinand; Sawicki, Jerzy; Vibration Problems ICOVP 2011

    2011-01-01

    This volume presents the Proceedings of the 10th International Conference on Vibration Problems, September 5-8, 2011, Prague, Czech Republic. Since they started in 1990 the ICOVP conferences have matured into a reference platform reflecting the state-of-the-art of dynamics in the broadest sense, bringing together scientists from different backgrounds who are actively working on vibration-related problems in theoretical, experimental and applied dynamics, thus facilitating a lively exchange of ideas, methods and results. Dynamics as a scientific discipline draws inspiration from a large variety of engineering areas, such as Mechanical and Civil Engineering, Aero and Space Technology, Wind and Earthquake Engineering and Transport and Building Machinery. Moreover, the basic research in dynamics nowadays includes many fields of theoretical physics and various interdisciplinary subject areas. ICOVP 2011 covers all branches of dynamics and offers the most up-to-date results and developments in a high-quality select...

  14. Vibration welding system with thin film sensor

    Science.gov (United States)

    Cai, Wayne W; Abell, Jeffrey A; Li, Xiaochun; Choi, Hongseok; Zhao, Jingzhou

    2014-03-18

    A vibration welding system includes an anvil, a welding horn, a thin film sensor, and a process controller. The anvil and horn include working surfaces that contact a work piece during the welding process. The sensor measures a control value at the working surface. The measured control value is transmitted to the controller, which controls the system in part using the measured control value. The thin film sensor may include a plurality of thermopiles and thermocouples which collectively measure temperature and heat flux at the working surface. A method includes providing a welder device with a slot adjacent to a working surface of the welder device, inserting the thin film sensor into the slot, and using the sensor to measure a control value at the working surface. A process controller then controls the vibration welding system in part using the measured control value.

  15. Automatic monitoring of vibration welding equipment

    Science.gov (United States)

    Spicer, John Patrick; Chakraborty, Debejyo; Wincek, Michael Anthony; Wang, Hui; Abell, Jeffrey A; Bracey, Jennifer; Cai, Wayne W

    2014-10-14

    A vibration welding system includes vibration welding equipment having a welding horn and anvil, a host device, a check station, and a robot. The robot moves the horn and anvil via an arm to the check station. Sensors, e.g., temperature sensors, are positioned with respect to the welding equipment. Additional sensors are positioned with respect to the check station, including a pressure-sensitive array. The host device, which monitors a condition of the welding equipment, measures signals via the sensors positioned with respect to the welding equipment when the horn is actively forming a weld. The robot moves the horn and anvil to the check station, activates the check station sensors at the check station, and determines a condition of the welding equipment by processing the received signals. Acoustic, force, temperature, displacement, amplitude, and/or attitude/gyroscopic sensors may be used.

  16. Vibrational Raman optical activity of ketose monosaccharides

    Science.gov (United States)

    Bell, Alasdair F.; Hecht, Lutz; Barron, Laurence D.

    1995-07-01

    The vibrational Raman optical activity (ROA) spectra of the four ketose sugars D-fructose, L-sorbose, D-tagatose and D-psicose in aqueous solution, which have been measured in backscattering in the range ≈250-1500 cm -1, are reported. These results are combined with those from a previous ROA study of aldose and pentose sugars in an attempt to establish new vibrational assignments and to verify old ones. The high information content of these spectra provides a new perspective on all the central features of monosaccharide stereochemistry including dominant anomeric configuration, ring conformation, exocyclic CH 2OH group conformation and relative disposition of the hydroxyl groups around the ring.

  17. Fuel Rod Flow-Induced Vibration Overview

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kang Hee; Kang, Heung Seok; Kim, Hyung Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2010-10-15

    To ensure fuel design safety and structural integrity requires the response prediction of fuel rod to reactor coolant flow excitation. However, there are many obstacles in predicting the response as described. Even if the response can be predicted, the design criteria on wear failure, including correlation with the vibration, may be difficult to establish because of a variety of related parameters, such as material, surface condition and environmental factors. Thus, a prototype test for each new fuel assembly design, i.e. a long-term endurance test, is performed for design validation with respect to flow-induced vibration (FIV) and wear. There are still needs of theoretical prediction methods for the response and anticipated failure. This paper revisits the general aspect on the response prediction, mathematical description, analysis procedure and wear correlation aspect of fuel rod's FIV

  18. Identification of Damping from Structural Vibrations

    DEFF Research Database (Denmark)

    Bajric, Anela

    Reliable predictions of the dynamic loads and the lifetime of structures are influenced by the limited accuracy concerning the level of structural damping. The mechanisms of damping cannot be derived analytically from first principles, and in the design of structures the damping is therefore based...... on experience or estimated from measurements. This thesis consists of an extended summary and three papers which focus on enhanced methods for identification of damping from random struc-tural vibrations. The developed methods are validated by stochastic simulations, experimental data and full-scale measurements...... which are representative of the vibrations in small and large-scale structures. The first part of the thesis presents an automated procedure which is suitable for estimation of the natural frequencies and the modal damping ratios from random response of structures. The method can be incorporated within...

  19. Vibration of Piezoelectric Nanowires Including Surface Effects

    Directory of Open Access Journals (Sweden)

    R. Ansari

    2014-04-01

    Full Text Available In this paper, surface and piezoelectric effects on the vibration behavior of nanowires (NWs are investigated by using a Timoshenko beam model. The electric field equations and the governing equations of motion for the piezoelectric NWs are derived with the consideration of surface effects. By the exact solution of the governing equations, an expression for the natural frequencies of NWs with simply-supported boundary conditions is obtained. The effects of piezoelectricity and surface effects on the vibrational behavior of Timoshenko NWs are graphically illustrated. A comparison is also made between the predictions of Timoshenko beam model and those of its Euler-Bernoulli counterpart. Additionally, the present results are validated through comparison with the available data in the literature.

  20. Anharmonic Vibrational Spectroscopy on Metal Transition Complexes

    Science.gov (United States)

    Latouche, Camille; Bloino, Julien; Barone, Vincenzo

    2014-06-01

    Advances in hardware performance and the availability of efficient and reliable computational models have made possible the application of computational spectroscopy to ever larger molecular systems. The systematic interpretation of experimental data and the full characterization of complex molecules can then be facilitated. Focusing on vibrational spectroscopy, several approaches have been proposed to simulate spectra beyond the double harmonic approximation, so that more details become available. However, a routine use of such tools requires the preliminary definition of a valid protocol with the most appropriate combination of electronic structure and nuclear calculation models. Several benchmark of anharmonic calculations frequency have been realized on organic molecules. Nevertheless, benchmarks of organometallics or inorganic metal complexes at this level are strongly lacking despite the interest of these systems due to their strong emission and vibrational properties. Herein we report the benchmark study realized with anharmonic calculations on simple metal complexes, along with some pilot applications on systems of direct technological or biological interest.

  1. Active vibration suppression of helicopter horizontal stabilizers

    Science.gov (United States)

    Cinquemani, Simone; Cazzulani, Gabriele; Resta, Ferruccio

    2017-04-01

    Helicopters are among the most complex machines ever made. While ensuring high performance from the aeronautical point of view, they are not very comfortable due to vibration mainly created by the main rotor and by the interaction with the surrounding air. One of the most solicited structural elements of the vehicle are the horizontal stabilizers. These elements are particularly stressed because of their composite structure which, while guaranteeing lightness and strength, is characterized by a low damping. This work makes a preliminary analysis on the dynamics of the structure and proposes different solutions to actively suppress vibrations. Among them, the best in terms of the relationship between performance and weight / complexity of the system is that based on inertial actuators mounted on the inside of the horizontal stabilizers. The work addresses the issue of the design of the device and its use in the stabilizer from both the numerical and the experimental points of view.

  2. Dynamics and vibrations progress in nonlinear analysis

    CERN Document Server

    Kachapi, Seyed Habibollah Hashemi

    2014-01-01

    Dynamical and vibratory systems are basically an application of mathematics and applied sciences to the solution of real world problems. Before being able to solve real world problems, it is necessary to carefully study dynamical and vibratory systems and solve all available problems in case of linear and nonlinear equations using analytical and numerical methods. It is of great importance to study nonlinearity in dynamics and vibration; because almost all applied processes act nonlinearly, and on the other hand, nonlinear analysis of complex systems is one of the most important and complicated tasks, especially in engineering and applied sciences problems. There are probably a handful of books on nonlinear dynamics and vibrations analysis. Some of these books are written at a fundamental level that may not meet ambitious engineering program requirements. Others are specialized in certain fields of oscillatory systems, including modeling and simulations. In this book, we attempt to strike a balance between th...

  3. Hydrodynamics induced vibration to trash-racks

    International Nuclear Information System (INIS)

    Sadrnejad, A.

    2002-01-01

    In conventional power plants trash-racks are provided at the intakes to protect the turbines. In pumped storage plants, the draft tube or tailrace must also have trash-racks to protect the units while pumping. Because the loads believed to cause many failures of trash-racks are dynamic in nature, it is important to understand the dynamic characteristics of trash-racks structures in general and a single rack in particular. The classical added-mass solution structure-fluid dynamic interaction is known as an approximate solution procedure. An accurate added-mass approach mixed with implementation in finite element framework is proposed. In this proposal, experimental conclusions, supported by theory, led to presentation of more accurate results in vibration of trash-racks. This numerical solution as a powerful method to solve such a complex problem can be employed to carry out dynamic characteristics of these structures while vibrating in water

  4. Ultrasonic Linear Motor with Two Independent Vibrations

    Science.gov (United States)

    Muneishi, Takeshi; Tomikawa, Yoshiro

    2004-09-01

    We propose a new structure of an ultrasonic linear motor in order to solve the problems of high-power ultrasonic linear motors that drive the XY-stage for electron beam equipment and to expand the application fields of the motor. We pay special attention to the following three points: (1) the vibration in two directions of the ultrasonic linear motor should not influence mutually each other, (2) the vibration in two directions should be divided into the stage traveling direction and the pressing direction of the ultrasonic linear motor, and (3) the rigidity of the stage traveling direction of the ultrasonic linear motor should be increased. As a result, the supporting method of ultrasonic linear motors is simplified. The efficiency of the motor is improved and temperature rise is reduced. The stage position drift is also improved.

  5. Resonant vibration control of wind turbine blades

    DEFF Research Database (Denmark)

    Svendsen, Martin Nymann; Krenk, Steen; Høgsberg, Jan Becker

    2010-01-01

    . The efficiency of the resonant controller is demonstrated for a representative turbine blade exposed to turbulent wind loading. It is found that the present explicit tuning procedure yields close to optimal tuning, with very limited modal spill-over and effective reduction of the vibration amplitudes.......The paper deals with introduction of damping to specific vibration modes of wind turbine blades, using a resonant controller with acceleration feedback. The wind turbine blade is represented by three-dimensional, two-node finite elements in a local, rotating frame of reference. The element...... formulation accounts for arbitrary mass density distributions, general elastic crosssection properties and geometric stiffness effects due to internal stresses. A compact, linear formulation for aerodynamic forces with associated stiffness and damping terms is established and added to the structural model...

  6. Damping of wind turbine tower vibrations

    DEFF Research Database (Denmark)

    Brodersen, Mark Laier; Pedersen, Mikkel Melters

    Damping of wind turbine vibrations by supplemental dampers is a key ingredient for the continuous use of monopiles as support for offshore wind turbines. The present thesis consists of an extended summary with four parts and appended papers [P1-P4] concerning novel strategies for damping of tower...... dominated vibrations.The first part of the thesis presents the theoretical framework for implementation of supplemental dampers in wind turbines. It is demonstrated that the feasibility of installing dampers at the bottom of the tower is significantly increased when placing passive or semiactive dampers...... in a stroke amplifying brace, which amplifies the displacement across the damper and thus reduces the desired level of damper force. For optimal damping of the two lowest tower modes, a novel toggle-brace concept for amplifying the bending deformation of the tower is presented. Numerical examples illustrate...

  7. Vibration Reduction System Using Magnetic Suspension Technology

    Directory of Open Access Journals (Sweden)

    Spychała Jarosław

    2015-01-01

    Full Text Available The article presents considerations concerning the construction of vibration reduction system using magnetic suspension technology. Presents the results of simulation, numerical and experimental the bearingless electric motor, for which successfully used this type of solution. Positive results of research and testing have become the basis for the development of the concept of building this type of active vibration reduction system , at the same time acting as a support for a technical object, which is a jet engine. Bearing failures are manifested by loss or distortion of their mass, which leads to a total destruction of the roller bearing, and thus reflected in the security. The article presents the concept of building active magnetic suspension to eliminate the bearing system of classical rolling bearing and replace it with magnetic bearing.

  8. How do nuclei really vibrate or rotate

    International Nuclear Information System (INIS)

    Andresen, H.G.; Kunz, J.; Mosel, U.; Mueller, M.; Schuh, A.; Wust, U.

    1983-01-01

    By means of the adiabatic cranking model the properties of the current and velocity fields of nuclear quadrupole vibrations for even-even nuclei in the rare-earth region are investigated. BCS correlated wave functions based on the Nilsson single particle Hamiltonian have been used. The current fields are analyzed in terms of vector spherical harmonics. The realistic microscopic currents show a vortex structure not present in the classical irrotational flow. The microscopic origin of the vortex structure is investigated

  9. Structural-Vibration-Response Data Analysis

    Science.gov (United States)

    Smith, W. R.; Hechenlaible, R. N.; Perez, R. C.

    1983-01-01

    Computer program developed as structural-vibration-response data analysis tool for use in dynamic testing of Space Shuttle. Program provides fast and efficient time-domain least-squares curve-fitting procedure for reducing transient response data to obtain structural model frequencies and dampings from free-decay records. Procedure simultaneously identifies frequencies, damping values, and participation factors for noisy multiple-response records.

  10. Isogeometric Shape Optimization of Vibrating Membranes

    DEFF Research Database (Denmark)

    Nguyen, Dang Manh; Evgrafov, Anton; Gersborg, Allan Roulund

    2011-01-01

    We consider a model problem of isogeometric shape optimization of vibrating membranes whose shapes are allowed to vary freely. The main obstacle we face is the need for robust and inexpensive extension of a B-spline parametrization from the boundary of a domain onto its interior, a task which has...... perform a number of numerical experiments with our isogeometric shape optimization algorithm and present smooth, optimized membrane shapes. Our conclusion is that isogeometric analysis fits well with shape optimization....

  11. Electronic Rydberg wavepacket effects on molecular vibration

    International Nuclear Information System (INIS)

    Hughes, I.G.; Meacher, D.R.

    1994-01-01

    Electronic wavepacket states of molecular hydrogen are considered which represent the situation of a spectator electron orbiting a molecular core. A quantum defect theory approach is used to determine the energy level structure, wavefunctions and molecular potentials, which is valid in regions where the quantum defects approach zero. In such a region the orbital motion of the wavepacket leads to a periodic variation in the molecular vibration frequency of the order of 100 cm -1 . Possible detection schemes are discussed. (author)

  12. Vibration of circular bladed disk with imperfections

    Czech Academy of Sciences Publication Activity Database

    Půst, Ladislav; Pešek, Luděk

    2011-01-01

    Roč. 21, č. 10 (2011), s. 2893-2904 ISSN 0218-1274 R&D Projects: GA ČR GA101/09/1166 Institutional research plan: CEZ:AV0Z20760514 Keywords : circular bladed disk * vibration * imperfection * nonlinear damping Subject RIV: BI - Acoustics Impact factor: 0.755, year: 2011 http://www.worldscinet.com/ijbc/21/2110/S0218127411030210.html

  13. Role of initial vibrational and rotational

    Indian Academy of Sciences (India)

    To investigate the effects of reagent vibrational and rotational states on the stereodynamical pro- ... Han et al.8 reported the total reaction cross-section, the ... ity k is contained in the xz plane, while the y-axis ...... Han B R, Yang H, Zheng Y J and Varandas A J C 2010 ... Zhang L, Chen M D, Wang M L and Han K L 2000 J.

  14. Blast vibration monitoring, July to December, 1983

    Energy Technology Data Exchange (ETDEWEB)

    1983-01-01

    The complexity of the vibration waveforms produced appears at this stage to preclude simple comparison of different blasts. A modelling approach is indicated from the preliminary experiments. The required elemental charge length and the steady state column length of ANFO in 381 mm holes must be determined for further development of a model. This information may be acquired by firing a number of charges of varying lengths with all other variables held constant.

  15. Microscopic theory of particle-vibration coupling

    Energy Technology Data Exchange (ETDEWEB)

    Colo, Gianluca; Bortignon, Pier Francesco [Dipartimento di Fisica, Universita degli Studi di Milano and INFN, Sez. di Milano, via Celoria 16, 20133 Milano (Italy); Sagawa, Hiroyuki [Center for Mathematics and Physics, University of Aizu, Aizu-Wakamatsu, Fukushima 965-8560 (Japan); Moghrabi, Kassem; Grasso, Marcella; Giai, Nguyen Van, E-mail: colo@mi.infn.it [Institut de Physique Nucleaire, Universite Paris-Sud, IN2P3-CNRS, 91406 Orsay Cedex (France)

    2011-09-16

    Some recent microscopic implementations of the particle-vibration coupling (PVC) theory for atomic nuclei are briefly reviewed. Within the nonrelativistic framework, the results seem to point to the necessity of fitting new effective interactions that can work beyond mean field. In keeping with this, the divergences which arise must be cured. A method is proposed, and the future perspectives that are opened are addressed.

  16. The high level vibration test program

    International Nuclear Information System (INIS)

    Hofmayer, C.H.; Curreri, J.R.; Park, Y.J.; Kato, W.Y.; Kawakami, S.

    1989-01-01

    As part of cooperative agreements between the US and Japan, tests have been performed on the seismic vibration table at the Tadotsu Engineering Laboratory of Nuclear Power Engineering Test Center (NUPEC) in Japan. The objective of the test program was to use the NUPEC vibration table to drive large diameter nuclear power piping to substantial plastic strain with an earthquake excitation and to compare the results with state-of-the-art analysis of the problem. The test model was subjected to a maximum acceleration well beyond what nuclear power plants are designed to withstand. A modified earthquake excitation was applied and the excitation level was increased carefully to minimize the cumulative fatigue damage due to the intermediate level excitations. Since the piping was pressurized, and the high level earthquake excitation was repeated several times, it was possible to investigate the effects of ratchetting and fatigue as well. Elastic and inelastic seismic response behavior of the test model was measured in a number of test runs with an increasing excitation input level up to the limit of the vibration table. In the maximum input condition, large dynamic plastic strains were obtained in the piping. Crack initiation was detected following the second maximum excitation run. Crack growth was carefully monitored during the next two additional maximum excitation runs. The final test resulted in a maximum crack depth of approximately 94% of the wall thickness. The HLVT (high level vibration test) program has enhanced understanding of the behavior of piping systems under severe earthquake loading. As in other tests to failure of piping components, it has demonstrated significant seismic margin in nuclear power plant piping

  17. Vertical structures in vibrated wormlike micellar solutions

    Science.gov (United States)

    Epstein, Tamir; Deegan, Robert

    2008-11-01

    Vertically vibrated shear thickening particulate suspensions can support a free-standing interfaces oriented parallel to gravity. We find that shear thickening worm-like micellar solutions also support such vertical interfaces. Above a threshold in acceleration, the solution spontaneously accumulates into a labyrinthine pattern characterized by a well-defined vertical edge. The formation of vertical structures is of interest because they are unique to shear-thickening fluids, and they indicate the existence of an unknown stress bearing mechanism.

  18. Statistical evaluation of vibration analysis techniques

    Science.gov (United States)

    Milner, G. Martin; Miller, Patrice S.

    1987-01-01

    An evaluation methodology is presented for a selection of candidate vibration analysis techniques applicable to machinery representative of the environmental control and life support system of advanced spacecraft; illustrative results are given. Attention is given to the statistical analysis of small sample experiments, the quantification of detection performance for diverse techniques through the computation of probability of detection versus probability of false alarm, and the quantification of diagnostic performance.

  19. Microscopic theory of particle-vibration coupling

    International Nuclear Information System (INIS)

    Colo, Gianluca; Bortignon, Pier Francesco; Sagawa, Hiroyuki; Moghrabi, Kassem; Grasso, Marcella; Giai, Nguyen Van

    2011-01-01

    Some recent microscopic implementations of the particle-vibration coupling (PVC) theory for atomic nuclei are briefly reviewed. Within the nonrelativistic framework, the results seem to point to the necessity of fitting new effective interactions that can work beyond mean field. In keeping with this, the divergences which arise must be cured. A method is proposed, and the future perspectives that are opened are addressed.

  20. Vortex induced vibrations in gapped restrainted pipes

    International Nuclear Information System (INIS)

    Veloso, P. de A.A.; Loula, A.F.D.

    1984-01-01

    The vortex induced vibration problem of gapped restrained piping is solved numerically. The model proposed by Skop-Griffin is used to describe the pipe-fluid interaction. The variational formulation is obtained modeling the gapped restraints as non-linear elastic springs. The regularized problem is solved using a finite element discretization for the spatial domain. In the time domain a finite difference discretization is used for the lift coefficient equatin and a Newmark discretization for the equation of motion. (Author) [pt

  1. Horizontal vibrations of piles in a centrifuge

    International Nuclear Information System (INIS)

    Bourdin, B.

    1987-01-01

    The aim of the thesis is the study of soil dynamics for important structures like nuclear power plants, offshore platforms, dams etc. Experimental results of horizontal vibrations on a pile partially anchored in a soil scale model put into a centrifuge are presented. Mechanical similitude conditions from equilibrium equations or rheologic laws are described. After a description of testing equipment (centrifuge, electrodynamic excitator) experimental results are interpreted with a model. Non-linearities on frequency response curves are characterized [fr

  2. Theory for Nonlinear Spectroscopy of Vibrational Polaritons

    OpenAIRE

    Ribeiro, RF; Dunkelberger, AD; Xiang, B; Xiong, W; Simpkins, BS; Owrutsky, JC; Yuen-Zhou, J

    2017-01-01

    Molecular polaritons have gained considerable attention due to their potential to control nanoscale molecular processes by harnessing electromagnetic coherence. Although recent experiments with liquid-phase vibrational polaritons have shown great promise for exploiting these effects, significant challenges remain in interpreting their spectroscopic signatures. In this letter, we develop a quantum-mechanical theory of pump-probe spectroscopy for this class of polaritons based on the quantum La...

  3. On the control of vibrations using synchrophasing

    Science.gov (United States)

    Dench, M. R.; Brennan, M. J.; Ferguson, N. S.

    2013-09-01

    This paper describes the application of a technique, known as synchrophasing, to the control of machinery vibration. It is applicable to machinery installations, in which several synchronous machines, such as those driven by electrical motors, are fitted to an isolated common structure known as a machinery raft. To reduce the vibration transmitted to the host structure to which the machinery raft is attached, the phase of the electrical supply to the motors is adjusted so that the net transmitted force to the host structure is minimised. It is shown that while this is relatively simple for an installation consisting of two machines, it is more complicated for installations in which there are more than two machines, because of the interaction between the forces generated by each machine. The development of a synchrophasing scheme, which has been applied to propeller aircraft, and is known as Propeller Signature Theory (PST) is discussed. It is shown both theoretically and experimentally, that this is an efficient way of controlling the phase of multiple machines. It is also shown that synchrophasing is a worthwhile vibration control technique, which has the potential to suppress vibration transmitted to the host structure by up to 20 dB at certain frequencies. Although the principle of synchronisation has been demonstrated on a one-dimensional structure, it is believed that this captures the key features of the approach. However, it should be realised that the mode-shapes of a machinery raft may be more complex than that of a one-dimensional structure and this may need to be taken into account in a real application.

  4. Vibrational spectra of charge transfer complexes of lead phthalocyanine

    International Nuclear Information System (INIS)

    Oza, A.T.; Patel, S.G.; Patel, R.G.; Prajapati, S.M.; Vaidya, Rajiv

    2005-01-01

    Infrared spectra of six charge transfer complexes of lead phthalocyanine (PbPc), namely, PbPc-I 2 , PbPc-TCNQ, PbPc-DDQ, PbPc-chloranil, PbPc-TCNE and PbPc-TNF, where TCNQ=7,7,8,8-tetracyano-1,4-quinodimethane, DDQ=2,3-dichloro-5,6-dicyano-p-benzoquinone, TCNE=tetracyano-p-ethylene and TNF=2,4,5,7-tetranitro-9-fluorenone have been studied in the range of 400-4000 cm -1 . The analysis of featureless absorption is carried out for studying transition across the Peierls gap of 0.225 eV. The electronic absorption envelopes at 1500, 1100 and 3400 cm -1 are found to have Gaussian shapes and not the degenerate oscillators, as found in purely organic conductors. There is a pairing of two electrons on phthalocyanine ligand as required in Little's model, and consequently, the electronic absorption envelope is a doublet. Electronic absorption envelope is a doublet showing two peaks at 1500 and 1100 cm -1 , indicating a two-electron problem in PbPc. Metal-ligand vibrations between 400 and 700 cm -1 lead to indirect transition between the valence and conduction bands and phonon-mediated coupling between metal chains and the side chains

  5. Time-varying output performances of piezoelectric vibration energy harvesting under nonstationary random vibrations

    Science.gov (United States)

    Yoon, Heonjun; Kim, Miso; Park, Choon-Su; Youn, Byeng D.

    2018-01-01

    Piezoelectric vibration energy harvesting (PVEH) has received much attention as a potential solution that could ultimately realize self-powered wireless sensor networks. Since most ambient vibrations in nature are inherently random and nonstationary, the output performances of PVEH devices also randomly change with time. However, little attention has been paid to investigating the randomly time-varying electroelastic behaviors of PVEH systems both analytically and experimentally. The objective of this study is thus to make a step forward towards a deep understanding of the time-varying performances of PVEH devices under nonstationary random vibrations. Two typical cases of nonstationary random vibration signals are considered: (1) randomly-varying amplitude (amplitude modulation; AM) and (2) randomly-varying amplitude with randomly-varying instantaneous frequency (amplitude and frequency modulation; AM-FM). In both cases, this study pursues well-balanced correlations of analytical predictions and experimental observations to deduce the relationships between the time-varying output performances of the PVEH device and two primary input parameters, such as a central frequency and an external electrical resistance. We introduce three correlation metrics to quantitatively compare analytical prediction and experimental observation, including the normalized root mean square error, the correlation coefficient, and the weighted integrated factor. Analytical predictions are in an excellent agreement with experimental observations both mechanically and electrically. This study provides insightful guidelines for designing PVEH devices to reliably generate electric power under nonstationary random vibrations.

  6. Vibration Suppression of Electronic Box by a Dual Function Piezoelectric Energy Harvester-Tuned Vibration Absorber

    Directory of Open Access Journals (Sweden)

    Sajid Rafique

    2014-04-01

    Full Text Available Over the past few years, remarkable developments in piezoelectric materials have motivated many researchers to work in the field of vibration energy harvesting by using piezoelectric beam like smart structures. This paper aimed to present the most recent application of a dual function piezoelectric device which can suppress vibration and harvest vibration energy simultaneously and a brief illustration of conventional mechanical and electrical TVAs (Tuned Vibration Absorber. It is shown that the proposed dual function device combines the benefits of conventional mechanical and electrical TVAs and reduces their relative disadvantages. Conversion of mechanical energy into electrical energy introduces damping and, hence, the optimal damping required by this TVA is generated by the energy harvesting effects. This paper presents the methodology of implementing the theory of 'electromechanical' TVAs to suppress the response of any real world structure. The work also illustrates the prospect of extensive applications of such novel "electromechanical" TVAs in defence and industry. The results show that the optimum degree of vibration suppression of an electronic box is achieved by this dual function TVA through suitable tuning of the attached electrical circuitry

  7. Determining the static electronic and vibrational energy correlations via two-dimensional electronic-vibrational spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Hui; Lewis, Nicholas H. C.; Oliver, Thomas A. A.; Fleming, Graham R., E-mail: grfleming@lbl.gov [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, Californial 94720 (United States); Kavli Energy NanoSciences Institute at Berkeley, Berkeley, California 94720 (United States)

    2015-05-07

    Changes in the electronic structure of pigments in protein environments and of polar molecules in solution inevitably induce a re-adaption of molecular nuclear structure. Both changes of electronic and vibrational energies can be probed with visible or infrared lasers, such as two-dimensional electronic spectroscopy or vibrational spectroscopy. The extent to which the two changes are correlated remains elusive. The recent demonstration of two-dimensional electronic-vibrational (2DEV) spectroscopy potentially enables a direct measurement of this correlation experimentally. However, it has hitherto been unclear how to characterize the correlation from the spectra. In this paper, we present a theoretical formalism to demonstrate the slope of the nodal line between the excited state absorption and ground state bleach peaks in the spectra as a characterization of the correlation between electronic and vibrational transition energies. We also show the dynamics of the nodal line slope is correlated to the vibrational spectral dynamics. Additionally, we demonstrate the fundamental 2DEV spectral line-shape of a monomer with newly developed response functions.

  8. Nonlinear convergence active vibration absorber for single and multiple frequency vibration control

    Science.gov (United States)

    Wang, Xi; Yang, Bintang; Guo, Shufeng; Zhao, Wenqiang

    2017-12-01

    This paper presents a nonlinear convergence algorithm for active dynamic undamped vibration absorber (ADUVA). The damping of absorber is ignored in this algorithm to strengthen the vibration suppressing effect and simplify the algorithm at the same time. The simulation and experimental results indicate that this nonlinear convergence ADUVA can help significantly suppress vibration caused by excitation of both single and multiple frequency. The proposed nonlinear algorithm is composed of equivalent dynamic modeling equations and frequency estimator. Both the single and multiple frequency ADUVA are mathematically imitated by the same mechanical structure with a mass body and a voice coil motor (VCM). The nonlinear convergence estimator is applied to simultaneously satisfy the requirements of fast convergence rate and small steady state frequency error, which are incompatible for linear convergence estimator. The convergence of the nonlinear algorithm is mathematically proofed, and its non-divergent characteristic is theoretically guaranteed. The vibration suppressing experiments demonstrate that the nonlinear ADUVA can accelerate the convergence rate of vibration suppressing and achieve more decrement of oscillation attenuation than the linear ADUVA.

  9. Vibration suppression of electronic box by a dual function piezoelectric energy harvester-tuned vibration absorber

    International Nuclear Information System (INIS)

    Rafique, S.; Shah, S.

    2014-01-01

    Over the past few years, remarkable developments in piezoelectric materials have motivated many researchers to work in the field of vibration energy harvesting by using piezoelectric beam like smart structures. This paper aimed to present the most recent application of a dual function piezoelectric device which can suppress vibration and harvest vibration energy simultaneously and a brief illustration of conventional mechanical and electrical TVAs (Tuned Vibration Absorber). It is shown that the proposed dual function device combines the benefits of conventional mechanical and electrical TVAs and reduces their relative disadvantages. Conversion of mechanical energy into electrical energy introduces damping and, hence, the optimal damping required by this TVA is generated by the energy harvesting effects. This paper presents the methodology of implementing the theory of electromechanical TVAs to suppress the response of any real world structure. The work also illustrates the prospect of extensive applications of such novel electromechanical TVAs in defence and industry. The results show that the optimum degree of vibration suppression of an electronic box is achieved by this dual function TVA through suitable tuning of the attached electrical circuitry. (author)

  10. The High Level Vibration Test Program

    International Nuclear Information System (INIS)

    Hofmayer, C.H.; Curreri, J.R.; Park, Y.J.; Kato, W.Y.; Kawakami, S.

    1989-01-01

    As part of cooperative agreements between the United States and Japan, tests have been performed on the seismic vibration table at the Tadotsu Engineering Laboratory of Nuclear Power Engineering Test Center (NUPEC) in Japan. The objective of the test program was to use the NUPEC vibration table to drive large diameter nuclear power piping to substantial plastic strain with an earthquake excitation and to compare the results with state-of-the-art analysis of the problem. The test model was designed by modifying the 1/2.5 scale model of the PWR primary coolant loop. Elastic and inelastic seismic response behavior of the test model was measured in a number of test runs with an increasing excitation input level up to the limit of the vibration table. In the maximum input condition, large dynamic plastic strains were obtained in the piping. Crack initiation was detected following the second maximum excitation run. The test model was subjected to a maximum acceleration well beyond what nuclear power plants are designed to withstand. This paper describes the overall plan, input motion development, test procedure, test results and comparisons with pre-test analysis. 4 refs., 16 figs., 2 tabs

  11. The High Level Vibration Test program

    International Nuclear Information System (INIS)

    Hofmayer, C.H.; Curreri, J.R.; Park, Y.J.; Kato, W.Y.; Kawakami, S.

    1990-01-01

    As part of cooperative agreements between the United States and Japan, tests have been performed on the seismic vibration table at the Tadotsu Engineering Laboratory of Nuclear Power Engineering Test Center (NUPEC) in Japan. The objective of the test program was to use the NUPEC vibration table to drive large diameter nuclear power piping to substantial plastic strain with an earthquake excitation and to compare the results with state-of-the-art analysis of the problem. The test model was designed by modifying the 1/2.5 scale model of the pressurized water reactor primary coolant loop. Elastic and inelastic seismic response behavior of the test model was measured in a number of test runs with an increasing excitation input level up to the limit of the vibration table. In the maximum input condition, large dynamic plastic strains were obtained in the piping. Crack initiation was detected following the second maximum excitation run. The test model was subjected to a maximum acceleration well beyond what nuclear power plants are designed to withstand. This paper describes the overall plan, input motion development, test procedure, test results and comparisons with pre-test analysis

  12. Silicon Micromachined Sensor for Broadband Vibration Analysis

    Science.gov (United States)

    Gutierrez, Adolfo; Edmans, Daniel; Cormeau, Chris; Seidler, Gernot; Deangelis, Dave; Maby, Edward

    1995-01-01

    The development of a family of silicon based integrated vibration sensors capable of sensing mechanical resonances over a broad range of frequencies with minimal signal processing requirements is presented. Two basic general embodiments of the concept were designed and fabricated. The first design was structured around an array of cantilever beams and fabricated using the ARPA sponsored multi-user MEMS processing system (MUMPS) process at the Microelectronics Center of North Carolina (MCNC). As part of the design process for this first sensor, a comprehensive finite elements analysis of the resonant modes and stress distribution was performed using PATRAN. The dependence of strain distribution and resonant frequency response as a function of Young's modulus in the Poly-Si structural material was studied. Analytical models were also studied. In-house experimental characterization using optical interferometry techniques were performed under controlled low pressure conditions. A second design, intended to operate in a non-resonant mode and capable of broadband frequency response, was proposed and developed around the concept of a cantilever beam integrated with a feedback control loop to produce a null mode vibration sensor. A proprietary process was used to integrat a metal-oxide semiconductor (MOS) sensing device, with actuators and a cantilever beam, as part of a compatible process. Both devices, once incorporated as part of multifunction data acquisition and telemetry systems will constitute a useful system for NASA launch vibration monitoring operations. Satellite and other space structures can benefit from the sensor for mechanical condition monitoring functions.

  13. Theoretical rotation-vibration spectrum of thioformaldehyde

    International Nuclear Information System (INIS)

    Yachmenev, Andrey; Polyak, Iakov; Thiel, Walter

    2013-01-01

    We present a variational calculation of the first comprehensive T = 300 K rovibrational line list for thioformaldehyde, H 2 CS. It covers 41 809 rovibrational levels for states up to J max = 30 with vibrational band origins up to 5000 cm −1 and provides the energies and line intensities for 547 926 transitions from the ground vibrational state to these levels. It is based on our previously reported accurate ab initio potential energy surface and a newly calculated ab initio dipole moment surface. Minor empirical adjustments are made to the ab initio equilibrium geometry to reduce systematic errors in the predicted intra-band rotational energy levels. The rovibrational energy levels and transition intensities are computed variationally by using the methods implemented in the computer program TROVE. Transition wavelengths and intensities are found to be in excellent agreement with the available experimental data. The present calculations correctly reproduce the observed resonance effects, such as intensity borrowing, thus reflecting the high accuracy of the underlying ab initio surfaces. We report a detailed analysis of several vibrational bands, especially those complicated by strong Coriolis coupling, to facilitate future laboratory assignments

  14. Isotope separation using vibrationally excited molecules

    International Nuclear Information System (INIS)

    Woodroffe, J.A.; Keck, J.C.

    1979-01-01

    Vibrational excitation of molecules having components of a selected isotope type is used to produce a conversion from vibrational to translational excitation of the molecules by collision with the molecules of a heavy carrier gas. The resulting difference in translaton between the molecules of the selected isotope type and all other molecules of the same compound permits their separate collection. When applied to uranium enrichment, a subsonic cryogenic flow of molecules of uranium hexafluoride in combination with an argon carrier gas is directed through a cooled chamber that is illuminated by laser radiaton tuned to vibrationally excite the uranium hexafluoride molecules of a specific uranium isotope. The excited molecules collide with carrier gas molecules, causing a conversion of the excitation energy into a translation of the excited molecule, which results in a higher thermal energy or diffusivity than that of the other uranium hexafluoride molecules. The flowing molecules including the excited molecules directly enter a set of cryogenically cooled channels. The higher thermal velocity of the excited molecules increases the probability of their striking a collector surface. The molecules which strike this surface immediately condense. After a predetermined thickness of molecules is collected on the surface, the flow of uranium hexafluoride is interrupted and the chamber heated to the point of vaporization of the collected hexafluoride, permitting its removal. (LL)

  15. Induced vibrations facilitate traversal of cluttered obstacles

    Science.gov (United States)

    Thoms, George; Yu, Siyuan; Kang, Yucheng; Li, Chen

    When negotiating cluttered terrains such as grass-like beams, cockroaches and legged robots with rounded body shapes most often rolled their bodies to traverse narrow gaps between beams. Recent locomotion energy landscape modeling suggests that this locomotor pathway overcomes the lowest potential energy barriers. Here, we tested the hypothesis that body vibrations induced by intermittent leg-ground contact facilitate obstacle traversal by allowing exploration of locomotion energy landscape to find this lowest barrier pathway. To mimic a cockroach / legged robot pushing against two adjacent blades of grass, we developed an automated robotic system to move an ellipsoidal body into two adjacent beams, and varied body vibrations by controlling an oscillation actuator. A novel gyroscope mechanism allowed the body to freely rotate in response to interaction with the beams, and an IMU and cameras recorded the motion of the body and beams. We discovered that body vibrations facilitated body rolling, significantly increasing traversal probability and reducing traversal time (P locomotor pathways in complex 3-D terrains.

  16. Flexural Free Vibrations of Multistep Nonuniform Beams

    Directory of Open Access Journals (Sweden)

    Guojin Tan

    2016-01-01

    Full Text Available This paper presents an exact approach to investigate the flexural free vibrations of multistep nonuniform beams. Firstly, one-step beam with moment of inertia and mass per unit length varying as I(x=α11+βxr+4 and m(x=α21+βxr was studied. By using appropriate transformations, the differential equation for flexural free vibration of one-step beam with variable cross section is reduced to a four-order differential equation with constant coefficients. According to different types of roots for the characteristic equation of four-order differential equation with constant coefficients, two kinds of modal shape functions are obtained, and the general solutions for flexural free vibration of one-step beam with variable cross section are presented. An exact approach to solve the natural frequencies and modal shapes of multistep beam with variable cross section is presented by using transfer matrix method, the exact general solutions of one-step beam, and iterative method. Numerical examples reveal that the calculated frequencies and modal shapes are in good agreement with the finite element method (FEM, which demonstrates the solutions of present method are exact ones.

  17. Free vibration analysis of corroded steel plates

    Energy Technology Data Exchange (ETDEWEB)

    Eslami-Majd, Alireza; Rahbar-Ranji, Ahmad [AmirKabir University of Technology, Tehran (Iran, Islamic Republic of)

    2014-06-15

    Vibration analysis of unstiffened/stiffened plates has long been studied due to its importance in the design and condition assessments of ship and offshore structures. Corrosion is inevitable in steel structures and has been so far considered in strength analysis of structures. We studied the free vibration of pitted corroded plates with simply supported boundary conditions. Finite element analysis, with ABAQUS, was used to determine the natural frequencies and mode shapes of corroded plates. Influential parameters including plate aspect ratio, degree of pit, one-sided/both-sided corroded plate, and different corrosion patterns were investigated. By increasing the degree of corrosion, reduction of natural frequency increases. Plate aspect ratio and plate dimensions have no influence on reduction of natural frequency. Different corrosion patterns on the surface of one-sided corroded plates have little influence on reduction of natural frequency. Ratio of pit depth over plate thickness has no influence on the reduction of natural frequency. The reduction of natural frequency in both-sided corroded plates is higher than one-sided corroded plates with the same amount of total corrosion loss. Mode shapes of vibration would change due to corrosion, except square mode shapes.

  18. Intracellular recording from a spider vibration receptor.

    Science.gov (United States)

    Gingl, Ewald; Burger, Anna-M; Barth, Friedrich G

    2006-05-01

    The present study introduces a new preparation of a spider vibration receptor that allows intracellular recording of responses to natural mechanical or electrical stimulation of the associated mechanoreceptor cells. The spider vibration receptor is a lyriform slit sense organ made up of 21 cuticular slits located on the distal end of the metatarsus of each walking leg. The organ is stimulated when the tarsus receives substrate vibrations, which it transmits to the organ's cuticular structures, reducing the displacement to about one tenth due to geometrical reasons. Current clamp recording was used to record action potentials generated by electrical or mechanical stimuli. Square pulse stimulation identified two groups of sensory cells, the first being single-spike cells which generated only one or two action potentials and the second being multi-spike cells which produced bursts of action potentials. When the more natural mechanical sinusoidal stimulation was applied, differences in adaptation rate between the two cell types remained. In agreement with prior extracellular recordings, both cell types showed a decrease in the threshold tarsus deflection with increasing stimulus frequency. Off-responses to mechanical stimuli have also been seen in the metatarsal organ for the first time.

  19. Occupant traffic estimation through structural vibration sensing

    Science.gov (United States)

    Pan, Shijia; Mirshekari, Mostafa; Zhang, Pei; Noh, Hae Young

    2016-04-01

    The number of people passing through different indoor areas is useful in various smart structure applications, including occupancy-based building energy/space management, marketing research, security, etc. Existing approaches to estimate occupant traffic include vision-, sound-, and radio-based (mobile) sensing methods, which have placement limitations (e.g., requirement of line-of-sight, quiet environment, carrying a device all the time). Such limitations make these direct sensing approaches difficult to deploy and maintain. An indirect approach using geophones to measure floor vibration induced by footsteps can be utilized. However, the main challenge lies in distinguishing multiple simultaneous walkers by developing features that can effectively represent the number of mixed signals and characterize the selected features under different traffic conditions. This paper presents a method to monitor multiple persons. Once the vibration signals are obtained, features are extracted to describe the overlapping vibration signals induced by multiple footsteps, which are used for occupancy traffic estimation. In particular, we focus on analysis of the efficiency and limitations of the four selected key features when used for estimating various traffic conditions. We characterize these features with signals collected from controlled impulse load tests as well as from multiple people walking through a real-world sensing area. In our experiments, the system achieves the mean estimation error of +/-0.2 people for different occupant traffic conditions (from one to four) using k-nearest neighbor classifier.

  20. Sum frequency generation for surface vibrational spectroscopy

    International Nuclear Information System (INIS)

    Hunt, J.H.; Guyot-Sionnest, P.; Shen, Y.R.

    1987-01-01

    Surface vibrational spectroscopy is one of the best means for characterizing molecular adsorbates. For this reason, many techniques have been developed in the past. However, most of them suffer from poor sensitivity, low spectral and temporal resolution, and applications limited to vacuum solid interfaces. Recently, the second harmonic generation (SHG) technique was proved repeatedly to be a simple but versatile surface probe. It is highly sensitive and surface specific; it is also capable of achieving high temporal, spatial, and spectral resolution. Being an optical technique, it can be applied to any interface accessible by light. The only serious drawback is its lack of molecular selectivity. An obvious remedy is the extension of the technique to IR-visible sum frequency generation (SFG). Surface vibrational spectroscopy with submonolayer sensitivity is then possible using SFG with the help of a tunable IR laser. The authors report here an SFG measurement of the C-H stretch vibration of monolayers of molecules at air-solid and air-liquid interfaces